The only places I know that look so warm are south Florida and California/AZ if you are in the US and hydroponic fertilizers are easy to get there.

My suggestion is to double check the MKP you mention you are using to be sure it really is what you think, and if you are needing to bump anything up slightly just let it be that.

It certainly looks like it is associated with a phosphorus deficiency, but those leaves are glowing like UV lights. Not sure what you mean about measuring the sulfur, but the battery acid is also suspect. If you actually are not in the US I'd be especially concerned in some other places if the impurities in that battery acid were not provoking the response. Phosphoric acid is probably what would do the trick for you, both bolstering the phosphorus and eliminating the possiblies of impurities in the other industrial acid, without necessarily needing the adjust the MKP if it is really OK. Personal preference: I simply don't trust car battery acid, gives me a bad feeling all over.

The production so far looks pretty awesome from where I'm standing and you may just need to change the nutes more often. Once possibility is that the P is OK, but the first to be used up.

You should also check into your source water. Is it too high in magnesium? Although sulfuric acid adds decent amount of sulfur, it is the single most efficient and cost effective acid you can use. Nitric will add a lot of Nitrogen, and Phosphoric becomes ineffective if your water is especially buffered at a basic pH. It doesn't seem like an overly huge amount of buffering since I think you suggest 0.6 mL is necessary per liter to offest the buffer to the extent you acidify to arrive at your working pH.

This post was edited by PupillaCharites on Thu, Jan 9, 14 at 1:56

Thanks for the quick reply.

I live in southern Europe. The pictures are taken in the past summer.The MPK i bought had absorbed water from the atmosphere and formed big rocks, so i had to crush them before i measure it. The tap water i used has 22 mg/l Mg and 104 mg/l Ca which was included in my calculations, also has 389 mg/l hydro-carbonates and 63 mg/l alkalinity m. The sulfuric acid is bough new from reputable company but after the bad taste of the tomatoes i wanted to do a experiment. As hydrobuddy calculated i roughly should be using 0.6mL sulfuric acid per Liter diluted solution to reach the 100ppm target. But when I add 0.6 ml sulfuric acid in 1L tap water (which is 350 ppm) and take a reading with my ppm meter it shows 750 ppm instead of 450. So i assume that's the cause of the bitter taste. I also tried mixing humic and citric acid which brought the ph to reasonable level but just for an hour or two and then jump back up. As i can see from the ph charts and nutrient availability, 6.3 ph is most optimal for the micro-nutrients uptake, but what happens if one uses chelated micro nutrients and, lets say leave the system at ph 7.5?Taken in account that the micro nutreients are available in wider range of the ph scale, is it possible to run the system at that high ph without any disadvantages overall plants health?

Don't use battery acid. In the US at least, there is the potential for it to be contaminated with lead.

You should really buy some pre-prepared fertilizer and ph up/down instead of trying to make your own. Maybe you could order it in powdered form to save money on shipping. Tomatoes have a complex nutritional requirement, so they would be the most difficult plants to concoct a nutrient solution like you tried to do.

I'm not against experimenting, but you should start with the easy way first. I don't even try to mix chem nutes myself; it's too easy to mess up. I have found, however, that organic fertilizers are much more forgiving if you are experimenting with your own mixture.

MKP is really hydroscopic so that is no surprise, and normal practice is to store it in a airtight container and doubly sealed in plastic. It will not degrade when it picks up water so it is good stuff, the only problem being you don't know how much you are adding since part of it is water.

The guys in Europe generally stick to EC measurements in mS/cm which is less confusing. I'm not doing tomatoes and I am not near my references, so I don't have the numbers off the top of my head. What I do notice is probably a typographical error in that there might be a near toxic amount of molybdenum, and I think the manganese is slightly high.

You seem to really have a handle on your water which is great. If there is a problem, it may be that your water is simply too hard. 104 ppm of calcium is is getting up there, and you say:

"389 mg/l hydro-carbonates and 63 mg/l alkalinity m."

I suppose you mean by hydro-carbonates what we call bicarbonate, and this would indicate your water actually is more buffered than I would want. I am not sure what the 63 ppm means, unless it is actually additional carbonate. To be honest in the US we usually just call it either all bicarbonate or all carbonate for convenience.

I would expect water with so much bicarbonate, if in fact it is bicarbonate, to give potentially spurrious readings, because a lot of that is not permanent hardness and will consume lots of acid and in this case I think phosphoric acid (if you can get it) for the initial adjustment of pH might be a bad idea, but once you get it adjusted let me suggest you try to use the MKP powder as your pH down if pH down is needed after it gets going, in your specific circumstances and you might get lucky and solve it that way.

Better yet just catch the rainwater if you can, perhaps off the roof, and use at least 1/2 rain if not 2/3 rain, but not more, plus the remainder with your water. This will cut your usage of acid to less than half of what you are doing now, which will greatly relieve any sulfur stress and contaminants from the acids.

In summary, as Cole says, it's convenient to have a commercially bought fertilizer because among other things it is removes the variable of your mixing. But you clearly have a good grasp of what you are doing, so I think you can do if that is really, really what you like to spend time doing (like me). As for the bitter taste, my suspicion is that you have too concentrated a fertilizer that is a little low on phosphorus for all that output during production. Even though both your responders hate battery acid, I'm guessing the difficulty you have is not the battery acid after all, but only your supplier might be sure. Your magnesium seems not to be the problem if the analysis you gave is right for the water so we can forget that suspicion. I really do think cutting the water to around 60/40 (rain/regular) will solve everything if you add just a bit more MKP. BTW, MKP turns into a block with a tiny amount of water so that's unclear how much water is in it. If you bought it basically dry and knew the original weight and what you used, weigh your stock again and you can probably make a very good estimate easily of how much water % is in it. If not, let me know and we can do something else I've been meaning to do. you're not the first one with the MKP blocks :-(

@Cole_Robbie

Good info, thanks for pointing out.
It's really hard to get hands on some good nutrients here, i did a research and call almost all the places i cud find in my area, but i cant find any NPK with reasonable NPK ratio and micro nutrients in it, or ph down/up. When i ask them about "specific" fertilizers they don't understand me and shrug theit shoulders (probably thinking i'm growing weed lol).
It happened to bought one "good" NPK 20-20-20 with bio-stimulants and amino acids 2% and seaweed extract 1% and good ratio of EDTA mincronutriens plus EDDHA Fe but i can't figure it out what dilution to use in hydro, every time i put a plant in the solution its stunned and does't grow, so I give up on that. I gave it on my grandma for the orchids, shows good results tho :)

As for buying from internet is also very difficult because my country is still out of the PayPal list. And the customs are also part of another story.
For example if i want to buy chemicals/nutrients that i can't find in the agronomy markets i have to pay ridiculous amount of money by invoice on a company for food/textile/paint chemicals. So i have to experiment :/

@PupillaCharites
Thanks for the great info.
The MPK i used was packed in cheap plastic bag. I crushed the rocks in powder form and put them in airtight jar. I might try to dilute the MPK first in distilled water and measure the ppm concentration, but i don't think that the meter can handle the high contents of dissolved salts, as the range of my meter is from 0 to 9990 (around 15 EC max).

For the Mn and Mo contend i used the trace element mixture which is as following:
Fe-EDTA: 6,90%
Zn-EDTA: 1,62%
Mn-EDTA: 3,40%
Cu-EDTA: 0,26%
Mo: 0,10%
With my first solution i had to use more of the mixture to reach the 3 ppm Fe target, but when i get the Fe-EDDHA i lowered the trace element mixture and made a little better balance in the micro nutrients , this is the output of hydrobuddy:
Fe: 3
Zn: 0.216
Mn:0.448
Cu:0.034
Mo:0.013
Also i think that when i added the Fe-EDDHA in the solution the leaves start to get the purple color.

I guess the hydro-carbonate is the combinations of the both, carbonates and bicarbonates.
The alkalinity m indicates how much acid it takes to bring down the ph to 4.3, if i read right from here
What's your idea about the MPK? I'm looking forward to the experiment :)

You should check your post and find the typographical error, you wrote 0.3 ppm molybdenum, but you really meant 0.03 ppm by looking at the ratios in your mixture of trace nutrients you posted = there is no problem with molybdenum so we can rule that out confidently now).

OK let me help a little more if I can. Let's talk just about two things.

*1st your sulfur suspicions and fear of too high sulfur.
*2nd our quick assay of our MKP

To talk about this, we should first say, we don't want to use ppm numbers from your meter. Your meter has a calibration that is not applicable for sulfuric acid and not applicable for MKP. The results will introduce unnecessary confusion.

1. Sulfur. Let me assume your meter is reading ppm of sodium chloride. Probably it is not precisely this, but this is very useful to estimate to give you an idea of the high readings that scared you (really they are probably not as bad as you think, but check over them to save me that trouble please.) For sodium chloride calibration with EC measured in mS/cm, the factor is about 485*EC=ppm(NaCl). For sulfur, it is about 42*EC=ppm. This means sulfuric acid is a very strong electrolyte and the ppm increase of elemental sulfur from sulfuric acid is really only 9% of what you read in that ppm meter. OK.

2. I will be using my personal MKP soon, so I will prepare a solution in distilled water of 1.00 grams of MKP in 999 grams of water, of my actual best stock which is typical of good MKP, to see how bad mine is. The you compare to me and we can have a beer over how bad it may be. But check yours. It should be EC about 0.725 mS/cm according some manufacturer info sheets, but we should be sure we are using the same MKP, which the good one is NPK rated (US NPK system is strange, really N,P205,K20) = 0-52-34. Be careful because there is other cheaper crap out there being sold of lower purity. So if yours is less than that in theory we can divide your EC reading by 0.725 and call the ratio your MKP purity. Now I'm done posting except maybe you do not have the conversion factor of your meter to know the real EC and you only see the ppm, so you will need to figure it out, or this method to estimate the MKP purity cannot be used. It is just an estimate, but if we measure the 1.00 gram well (you can also put 10.0 gram in 10 liters to get the same but waste material).

I've never checked directly the EC of my good MKP, so I will be more confident to see my reading from my good supply of 0-52-34 material instead of what some documents say even though they are supposed to be right, I prefer to see directly what's going on with this. If you want to go ahead and measure yours if you have the distilled water and post that would be great. I can use a little more water and MKP in a reservoir in 2-3 days the way one is behaving, so I can measure mine precisely then and help/compare with you and we can solve the MKP purity doubts together. But you must get the EC in mS/cm precisely, of course.

Thank you for taking the time to solve my problems. I appreciate it.

Currently i don't have an EC meter. The NaCl here is supplemented with 20 mg iodine per kilogram so i'm afraid that i can screw things up if i calibrate. The meter is not used much tho. Hopefully will have a good result. The MPK labels says:
P2O5 52%
K2O 34%
AND
As 100ppm
Cd 0.025ppm
Ca 100ppm
Mg 100ppm in EDTA form
Which was not included in my calculations, i did't know until now, when i read the label :/
I will have to find good quality MPK. Thank you again

My MKP does not mention any arsenic on the label, literature or MSDS. 100 ppm sounds high for As, maybe it is ppb? Still, if I am interpreting how you wrote the label info properly, that for the amounts you are using the Ca and Mg are negligible 100 ppm is only 0.01% if I got the decimal right, so just to get a milligram you need to use 100 grams of the MKP, which is why it is negligible. The 0-52%-34% on your label indicates it is high purity though.

I haven't had to calibrate my EC meter, as I keep getting very similar results since the day I bought it - this is for the working solution - which is the normal measurement I take. That 20 ppm of iodine again, will be negligible amount in a solid kg of sodium chloride and you don't need to use the meter's calibration function, only to put 1.00 grams of NaCl in distilled water and make your own calibration factor, and then do it again if you want to be perfect with 1.5 g and then 2 grams for example. The reading in that small interval range is linear enough, and if you want to check your calibration. I agree it is better you wouldn't calibrate with that NaCl, because besides the iodine, there probably are other impurities. Not much, only about 1%, so these are minor usually, nothing to worry about.

So to do that, all you have to do is record the reading for 1.00 gram good table salt in 0.999 liter distilled water. Better to take the blank water reading too, and actually a low reading water is probably fine to use if you correct for the blank, like rain is perfect, and then just subtract the plain (blank) water reading to get the increase from the NaCl. Then record the NaCl increase, and repeat again with MKP the same way and just say the ratio of increase of 1 gram MKP to the ratio of increase of 1 gram NaCl. I explain badly I think, but it’s really simple, just two measurements and we could know.

Since it is a nice day today and rained into my strawberries they didn't need the extra water so I just added the MKP crystals directly that they needed. If you had said something I would have covered them, but that is more work, so I let nature do the refilling. But if you want to do this some time, just tell me, I can always work it in and the more people that compare what they are getting the more sure we can be.

Best of luck and if you come back here please say what region of Southern Europe which is always interesting to hear. I bet some nice warm place in summer on the Adriatic Sea :-), which makes extra fun to try to help!

I was little busy lately configuring the home network and reinstalling windows on the pc's.

These are the results from the ppm experiment:

The reading of 1gr NaCl in 999mL distilled water first was 1270ppm, then i calibrate the meter to 1000ppm after that i added 1gr more NaCl in the 999mL distilled water and the reading was 2000ppm

for the other testing i had to use tap water which is 270ppm
so:
500Mg NaCl in 1L tap water turned out 724ppm
1g NaCl in 1L tap water turned out 1280ppm
1g MPK in 1L tap water turned out 600ppm

Tomorrow i will be making fixture for 3x56w fluorescent bulbs indoors to provide good light source for the seedlings. I can't find any rockwool cubes so i will start them in peat and after 2-3 true leaves appear i plan to transplant them in passive system where they will stay after the last danger of frost pass.

Currently I'm working on automation project using arduino (microcontroller) which basically takes readings from various sensors and do thing like "when temperature reading is 30C turn on the fan" or you can use it for ph controlling with peristaltic pumps and connect it to the internet to monitor and control things which i find fun to do.

Hope i do well this year, btw I'm from Macedonia, Skopje. Feel free to tell me if i need to do any other experiment for the MPK test, i have one brita carbon filter laying around somewhere, i can make another test solution if needed.

No problem, I did a little lookup table PIC project myself for solution heating in day and night my differential depending on ambient temperature, with a TO-92 case temperature sensor that costs about $1 and a $0.10 photocell, but I got too busy to make it in a permanent enclosure, but it will be fun to do some time in the future.

Also at that time I also got an arduino I never used that I was going to hook up to some already made pH interface with temperature made by some guy Reza Hussein on the internet that looked like a nice board very cheaply, but I never advanced on that after I got very stable pH behavior by adjusting my fertilizer proportions instead and can use the chemical indicator cheap and easy without another electrical connector too, but really I would like to use the arduino hardware sometime since I paid for it.

On the MKP test that's great you decided to do it, please explain to me exactly what is being measured to be sure I understood. I'll do it when I get a chance, and I will bake my NaCl in the oven a little because here in Florida it is very humid.

I couldn't be sure if you actually recalibrated (Hope not, unless you have some real standard calibration solutions or software reset in the meter). I think yours might be a 640 non-linear TDS conversion, BTW. Also I wasn't absolutely sure if you already subtracted the tap water reading or if you included the tap water baseline measurement in the ppm the meter returned and you wrote as the result. So please just be precise what those represent, because I don't want to assume. As long as you make the measurements at the same temperature we should be fine, but be careful with the temperature because every 5 C degrees is a 10-15% difference in EC, and the meter itself may already correct which will get confusing if you don't make sure the solutions are the same temperature when measured.

If it all goes right, I think you can just use the EC factor 2.73*MKPppm=NaClppm if you can relate all readings back to NaCl. (NaCl is the higher EC per gram by nearly triple). The problem of not using something close to distilled water is other electrolytes in your tap might might interact with the pH and chemical equilibria, but we can try and see. But a simple carbon filter will not de-ionize the water, so clean rain is better.

Skopje, no sea, but a great and interesting place! Nice to have you here :-)

This post was edited by PupillaCharites on Fri, Jan 17, 14 at 3:01

i calibrated the meter with homemade calibration solution from NaCl. The meter has ATC but the temperature reading is little slow so i waited about a minute between readings to get accurate temperature compensation. 1g MPK subtracted from tap water is 320ppm. Hope we can compare the results soon.

Sure, I will do it soon, on the next opportunity I need to open the MKP. Let me give you some more complementary information about MKP which may be helpful.

If you have a great deal of water picked up in it due to storage in clean but humid conditions, and access to an oven, you can dry it out.

Consider high grade MKP, to have the 34% potassium fertilizer rating must be over about 98.2% purity, or in general terms, not less than 98% pure. The 98% purity of the newly sealed dry product from a new supplier will not lose more than 1% of its weight upon drying.

The drying conditions recommended during the assaying of it are at 105 C for 4 hours to check the loss of water.

If you can safely dry it in an oven where the air is still, this is an alternate way to check the purity, just by using a carefully tared pre-dried weighing pan. 1% is the maximum mass loss, but it likely is less, ok. If you were to dry it and find for example 10% weight loss, on your dried sample, you could add approximately 12% additional from your wet stock to adjust for the purity 0.900*1.12=1.008.

Considerations for doing this:
Monopotassium phosphate, KH2PO4 dry, has a melting point of the salt at slightly over 250 C degrees. There is no decomposition of it at or below its melting point, and not even under 350 C. At 400 C it will chemically decompose by losing the hydrogen in its chemical formula reacting with the phosphates, generating water and leaving potassium metaphosphate along with dangerous phosphorus oxides which are *extremely* irritant. This means you could probably also dry it out at 120 C for only 2 hours or less, better flattened out, but the impurities would be somewhat unknown, which is why the 105 C temp is used, and also because driving out the moisture has some diffusion limitations favoring a longer bake at lower temperature.

One limitation is that if you have a large sack, it probably has not picked up water in a uniform way. The core may be pure where the outside or wherever the humidity most enters may be the worst. Whether you crush it together or not depends on whether you want to have drier product from the center or don't mind mixing it all together by crunching down and mixing the 'blocks' while they are still in the bag and in the future sealing it in an outer container better for storage.

The above non-uniform limitation is also applicable to any assay including our attempt with EC, so several areas might need to be checked to know it perfectly well, or it would have to be completely squashed into a powder again nside the bag (outside).

A good face mask/respirator is in order wherever any opportunity exists to breath this stuff in, but to put it into perspective, most other fertilizer salts and complete mixtures are much more risky than this one.

You don't want to breath MKP much generally, as it is mildly irritating, so it is an iffy question as to the safety of doing this carefully in the kitchen oven of course provided that oven does not utilize any moving air currents. Even a small natural heat convection movement in a propane oven, for example, can bring airbourne powder in contact with the flame which would result in decomposition vapors.

This post was edited by PupillaCharites on Sat, Jan 18, 14 at 12:10

I appreciate your help, you are well educated in this field

I'm new in chemistry and i don't understand much about it. I still learn. I do my measurments with This small pocket scale.

can I compare the percentage gained in my mpk to the dry mpk and add that as following?

of course i will crush the mpk block again, mix the powder well, store it in airtight zip-lock bag and do a couple more experiments in distilled water, if this is alternative works.

But if we take the previous experiment as an example:
my (humid) 1g mpk in 1L water has 320 ppm
the dry 1g mpk product in 1L water has total of 514.9 ppm

so my question is :
if we calculate the percentage as following

514.9 (the dry mpk)
320 (the humid mpk)

514.9 - 320 = 194.9
(194.9/514.9) x 100 = 37.8 %

can i add 37.8% (humid) mpk wight to my stock solution to reach the real P and K content? Or it's more complex then this? i'm bad at math and chemistry, i barely know the basics. I can see that we have two elements which idk if they absorbed water(weight) equally and if the calculation is acceptable for future use. 37.8% addition seems a lot.

Yes, you can do something like you propose in the calculations. All ths is assuming there is a lot of water in there, which we still need to prove (unless you've already).

If the MKP takes up water, there is no need to actually dry it all out if you know how much water is in it from just a small sample, just add extra to cover the lower purity.

I'm not sure where the 514.9 is coming, if it is just something you are using as a hypothetical example, or if it is coming from somewhere you measured or calculated. Because If your meter is showing 1 gram of NaCl per liter at 1000 ppm, I would guess thatit would show 1 gram of MKP at 367 ppm using the same calibration (this is in theory and I will verify this against my own MKP when I next use it to compare the real material I use to be sure, instead of numbers from a chemical handbook). That is not so different from your 320 ppm you explained how you measured. So by electrical conductivity I am thinking maybe your purity is roughly 320/367*100% = 87% (and we can call 13% water). So to put one gram in of that we just add 1/0.87 gram = 1.15 grams so the net amount of pure MKP is 1.00 gram and 0.15 of water we are not worried about.

Alternately if you can dry it and find for example 1.00 grams of humid material is dried to 0.83g for some hypothetical example just to discuss some numbers, you do the same thing, not eactly add the missing 0.17g, but somthing close, you want a gram you must add 1/0.83= 1.20 grams, just a little more. This is an independent (alternate) to using the EC, if you can safely test it with your scale. Your scale looks ok, funny, the same page has the scale I am using for the hydroponic quick small mass measurements my scale

If you are using polythene bags, they are actually not as great for long term storage as some other options, because water eventually diffuses through them when a dessicant is inside like MKP. So if you must use those, be sure to carefully put a well sealed bag into a well sealed bag. We have the same problem in the USA, when the old formula for Saran plastic (that old Saran was so much more water impermeable) was changed to all polythene (PE). Most guys with fertilizer buy a 19 liter bucket used for storing food that has a good sealing lid. It is common here for storing food (like cereals and grains) in case of a storm emergency, or also to put pet food like dog biscuits. Here is a girl demonstrating the "gamma seal" product that is common here, it is what I am using. gamma seal demo

This post was edited by PupillaCharites on Sun, Jan 19, 14 at 2:35

I used the number 514.9 as the sum of 227.58 ppm P and 287.32 K per 1g/L mpk (as i read from HydroBuddy) but i'm not sure if that applies to this case ?

Finally finished baking the mpk for 4 hours, the oven may not been precisely 105C the whole time. I used 30g sample, just to reduce possible errors in the scale. After baking for 4 hours the dry product had 28.97g so approximately 3.4% water evaporated during the process.

I'm still concerned about the purple coloring, it may because the lower temperatures when i grown the tomatoes, i think that the tomatoes have trouble adsorbing phosphorus at normal rates when exposed to lower temperatures. When i read Howard M. Resh's book, in one chapter he points:
"In tomatoes the appearance of purple coloration on the
undersides of the lower leaves indicates temperatures are too low"
so somehow, botanically the deficiency and the low temperature may be related.

I finished my light fixture and it shows amazing results, i had one chili paper on my south facing window planted in soil for more then a month, and it has grown 10 leaves, for only 2-3 days it grown 5 more leaves under the fluorescent bulbs. Can't wait to start the tomato seeds. This time i bought different cherry variety and full sized "ox-heart" Italian tomato seeds. Hope they do ok in the same system.

Leave a message on this post or contact me via e-mail when you make measurement, so we could get even more precise. Always new stuff to learn here. Sorry for my bad English, it may be hard to read. It's not my mother-language, i hope you understand. Have a nice day :-)

Ah ha, That's how you created the 514.9 number. I do not use the hydrobuddy program for formulating since it is very clunky interface that is much easier in a spreadsheet since the math is only a little multiplication and division. I do use it for cracking other people's formulas because I think it has a somewhat stable linear optimization subroutine, which is really helpful, in some situations. So I can't comment on the accuracy of the numbers but I can check its math for this case against ours.

Your numbers apply, but not the way you added them, so while your calculation is wrong, we can fix it and see what it should be. Let's use the 228 ppm P and 287 ppm K. The molecular weight of MKP is 136 g/mol. It has one K and one P which are 39 + 31 = 70 g/mol and other atoms that aren't included but have additional mass. So P & K represent 51.5% of the true ppm of 1 gram per liter. Take your 514.9/0.515 = 1000.0 ppm. Perfect. No surprises, the program is correct since 1 g/L is 1000 ppm. Plus, I have learned from these numbers that you are using purity = 100% MKP, which is best laboratory grade, not what we have (but ours is about 98%, ok)

But, this is the GIANT problem with trying to use a ppm calibrated meter for anything. It doesn't work, unless you calibrate it with the material you are using. Like when you calibrated it with NaCl, remember you made 1 g/L and you got 1000 ppm NaCl and you put in 2 g/L and measured 2000 ppm. You calibrated your meter for NaCl and only NaCl. Now you measure 1 g MKP in a liter. The meter only reads ppm so you stick it in and it says, "this feels like 320 ppm of NaCl". But it has nothing to do with MKP, because it is thinking only the conversion factor for NaCl you calibrated it with. So it does not apply. Therefor there is a huge difference in conductivity between MKP and NaCl. For an equivalent weight I've estimated it from the chemical handbook to be 36.7% as conductive, so in my way your dry MKP is not 514.9 (completely incorrect assumption, forget that one), but rather if your EC is converted to 1000 ppm forNaCl, I expect it will read 367 ppm using the NaCl calibration for 1 g/L MKP (36.7% of 1000 ppm) which reflects the fact that NaCl has a much greater property of electrical conductivity.

(1) Based on your EC data, I got your purity as 320/367 = 87%.

However, based on your data from the oven drying test - I have complete confidence in you on your technique and a few degrees will not be a significant difference. You get by method of drying:

(2) Based on your drying data, your math was 28.97/30.00 = 96.6%.

So, the question is now, two methods and two different results, which do we trust? Ha ha! Not really funny, just time to think. There is more variability in the conductivity in the measurement error, perhaps it was not 320 but 330? That small difference you will have difficulty confirming can represent not 87% but perhaps as much as 91%. Add the other variables like temperature and the uncertainty of the tap water and it becomes doubly messy. But that doesn't mean the MKP is perfect, either. First, when looking at small numbers, let's not forget its specification is 98%, not 100%. So that makes the purity of your assay really about 98 - 3.4 = 94.6% (approximately). And after we think very hard about this all we can find other reasons to doubt even a little more. So, what would I do in that situation? I would say the purity is between 90 - 95%. I would ask myself "what acid am I using to adjust pH?" answer: sulfuric in your case. Well, I am not adding phosphorus when using pH down, like most other people in the US, UK, Australia, etc., and when my plants have high demand in fruiting they exhibit purple leaves which point to phosphorus deficiency. Your formula is high in KNO3 and potassium, but so I might increase CAN a few ppm and drop back a few ppm of KNO3 to accomodate a little more MKP in the formula without going bananas on potassium. Or if I had MAP, monoammonium phosphate, I'd include an incremental addition of about 6 ppm of ammonium N (= 13.3 ppm P). Tomatoes like high K, but also we must keep the ratios under control, and that is why I would do that since MAP adds a lot of phosphorus and no additional potassium which you cover with all that KNO3 in your formula.

I know this is a little complicated, but it is all logical if you can understand my language. I hope you don't need Google translate! Any question just ask and it will be my pleasure to help, because your concern is fixing the purple problem. Now we have approximated the Phosphorus from MKP question, and the easy answer to that is it is contributing to the problem, but the big picture I think is you have a huge fruit load during maximum production time, your plants love your fertilizer and temperatures and they are running out of phosphorus under those conditions only duuring high production. So when you make your formula just add 10% extra humid MKP for whatever your dry formula calls for and consider adding a little MAP to the formulation, and using at least 50% rain, both of those will reduce the amount of H2SO4 substantially and your formula will likely be in much better balance during the high production.

I am sure of this, the only thing is to double check my MKP to compare with you. So we can get it over with, in two-three days I'm supposed to use nitric acid to lower my pH, but I can be OK with 1 gram of MKP instead. Unfortunately I'd like to remove water, not add water in my reservoir, so when I open the MKP to put in the res, I'll put the powder in and I'll make a separate liter of 1 g/L MKP and save it for later, but take the EC to complete out experiments and also tell me either my MKP is great, or maybe do a little thinking about what I am doing too. MKP really is a difficult compound to keep dry. Another experiment we have to do some time is put some in the air for a while and then see how much water it absorbs. But I'm afraid it may absorb more than it's own weight like that :(

Also, don't forget the earlier suggestion, which is another possibility instead of MAP and worrying about CAN/KNO3 at all. That was, you can use sulfuric for the initial fixing of the pH, but after the initial adjustment, all later adjustments until the next change can be made with phosphoric acid if you can get some cheaply enough there.

This post was edited by PupillaCharites on Mon, Jan 20, 14 at 23:39

I wish I had enough of an education in chemistry to fully appreciate the fine information in this thread. I feel like an illiterate man staring at classic literature.

The tiny bit of scientist in me would love to see you experiment with your chemical concoction versus an unscientific organic one. If I couldn't buy nutrients, I would start scraping up the poop of various animals, composting it, and making tea. Expensive organic hydro nutrients like Earth Juice are made of a pretty disgusting mix of dead animal parts. But it works. I don't know yet if it makes a better product, or is more commercially viable, but like I said, I am just enough of a scientist to wonder, even though the chemistry involved is over my head.

Cole, those organic formulations are really a can of worms, and the pun is the least of it. I also would really love to get a handle on the organics and make my own, but it really is another world in what makes them tick. I'm safe with a bunch of salts, but the moment symbiotic microbes take front seat, I get totally psyched out. I have always been feeling ignorant in the sense I suspect that a lot of them are just a cocktail of compost I could make, but then there is some little trick of culturing a colony of one secret recipe microbe that everyone but me knows about.

What would be something we could do with enough motivation, is look at some of the ones that give good results and just take a random sampling of how much the elemental composition actually varies for a particular single good product. That is something I'd love to know and could be gotten. I really can't buy that there is any magic formulas as much as good ranges that are very forgiving, and maybe a little art in perhaps pretreating it by incubating with secret microbe ingredient #X which would be as much as I can image is hidden away in the cloak and dagger and cult mystique following some of these products get.

Imagine sticking a bunch of worms in the oven to see how much they dry out :-0!

We may take the aquaponics as good alternative and organic type of hydroponics. When i got hooked up by the "hydroponics hype" i did not know anything about aquaponics, i only knew that there are fishes and plants in the same water. Any info that i came across the internet was too long and complicated the whole thing seemed like big mess to me, so i focused on doing nutrients from salt which i tough would be easier. Aquaponics is not complicated as i tough. Just feed the fish daily and wait for about 3 months for the nitrification process to start and then you are "on the boat". I think that is even more forgiving then straight hydroponics. I plan to try it out some day. Always some new tweaks around the system which is fun time to sped and very awarding.

PupillaCharites, thanks for the great info I will try to balance the CaN/KNO3 untill i find MAP. Can you recommend me some spreadsheet for doing this ?
Also i wanted to ask you, if you are sure about the sulfuric acid you said about earlier, if i understand you, you said that hydrobuddy calculated ok, but my ppm meter which i used is not suitable for that kind of measurements as i was attempting. In my formulation there should be 109 ppm S. Hydrobuddy calculated 64.5 mL sulfuric acid per 100L water which also act as ph down to bring the ph to 5.5. Catching rain from the roof will be tricky but after i cover the balcony and buy some more buckets, it will be my first priority

Damjan, any spreadsheet like Excel, etc. Here's a simplified example you can expand to how you like. Let's say you put the salts in the columns (with the weight of each salt in the header (row#1) and your nutrients in the rows below(row#3,4,5, etc.). For example, CAN can be in the second column and MKP the third; the rows can be N(NO3-); N(NH4+); P; K; Ca. All of these are for the element. N(NO3-) is elemental N derived from nitrate (NO3-) sources, for example, NH4+ refers to ammonium sources for N, which is generally the only element we look at by it's two major sources.

To make the CAN row we understand CAN= Calcium Ammonium Nitrate (not to confuse with Calcium nitrate tetrahydrate, which is commonly not easy to buy in powder fertilizer grade). Then For CAN we look at the sack, it says in my case perhaps, brand: Yara 15.5-0-0 19Ca, Guaranteed Analysis N(NO3-)=14.4% N(NH4+)=1.1% Ca=19.0%. So my first CAN column entry in the first N(NO3-) row will be N(NO3-)

For 10 grams of CAN, it looks like this:

10.00
CAN
N(NO3-) =10*0.144
N(NH4+) =10*0.011
P =10*0
K =10*0
Ca =10*0.190
Mg =10*0
and =10*0 for all the other elements below, S,Fe,Mn,B,Zn,Cu,Mo,Na,Cl and if you have, Si

We can repeat for the next column perhaps 3 grams of MKP 0-52-34 which has this analysis on the bag P=22.5% K=28.2%. With only P & K you must get the element %, not the marketing percent (52&34), because only these two elements are usually marketed inflated to include the extra weight of oxygen for illogical marketing reasons when buying fertilizers containing P,K.
3.00
MKP
N(NO3-) =3*0
N(NH4+) =3*0
P =3*0.225 (not use 0.52)
K =3*0.282 (not use 0.34)
Ca =3*0
Mg =3*0
and =3*0 for all the other elements below, S,Fe,Mn,B,Zn,Cu,Mo,Na,Cl and if you have, Si

The next column after MKP will be the totals (sum) of each salt's contribution in this abbreviated example, we will have only

N(NO3-) 1.44g
N(NH4+) 0.110g
P 0.675g
K 0.846g
Ca 1.90g

Then the next column will be the ppm for each elemental total by dividing the amount of water and converting to ppm. If we use 10 liters (=10 kg of water), for N(NO3-) it will be =1.44/10*1000 and the cell will have the calculation value of 144 ppm for N(NO3-). Try this and you will get 11 ppm for N(NH4+), and the others. The ppm conversion is simple, our division is g/L, but ppm is sometimes called "mg/L", and that's why we have to multiply by 1000, to convert the grams to mg.

Once you set up your first spreadsheet for the chemicals you have, in seconds you can copy/paste any formulation you want and change the weights and cell that contains the liters total of the reservoir. There can be a small correction when using very concentrated solutions (because if you have very concentrated solutions, like 5% MKP for example this is 50000 ppm and really should be measured as 950 grams of water and 50 grams of MKP, so there is a small error and the 50 grams of MKP in 1 liter is really 476 ppm (50/1050). But you can ignore this until you you are ready to make this small adjustment which for dilute solutions is not necessary. 144 ppm N is really 1.44g in 9998.56g water, so the error here dilute is not significant: it is really 143.98 ppm, but we can't even measure the difference with our scales. It is only significant when making more concentrated solutions, not working solutions.

This post was edited by PupillaCharites on Thu, Jan 23, 14 at 13:38

I don't exactly understand the sulfuric acid question, because it sounds to me like your hydrobuddy is telling you how much sulfuric acid you need to get to pH 5.5, but I am not aware that hydrobuddy is calculating neutralization equivalents in acid-base equilibrium. So explain a little better the concern, please. If I were you I would prioritize the rain water before buying another salt (MAP), because, the water analysis you gave has very high Calcium and using only half and half of the waters you can be so much more flexible with your use of CAN. (You can use more CAN and less KNO3 to get your N(NO3-) target ppm Then there will be a lower K from less KNO3, which you compensate now with more MKP and the extra phosphorus will be naturally there from more MKP without buying MAP or phosphoric acid. Look at what I made a few weeks ago for free rain collection, if it can give any idea:

I got 4 cm of rain the other day, after about 0.5 cm fell cleaning the air and my blue cover, I put the three purple collection tubs there and collected more than 120 liters of rain at 0.002 mS/cm EC. (1 ppm !)) from about 3.5 cm of rainfall. And I needed the cover anyway to protect the reservoirs from overflowing from too much rain.

This post was edited by PupillaCharites on Thu, Jan 23, 14 at 14:26

Because I need to start a new work project I may not have time to answer in the next week too much so I am going to give you a little demonstration which I think you can use to solve your own question about sulfuric acid, no matter what the problem is, I am confident in the theory of everying I said but to be honest I am not reviewing it all to check for a typographical error.

Please let's make this the last time we talk about Hydrobuddy. It is a great program for many people, but I personally find it especially awkward to use for simple recipes because I like to see my data in front of me all 100% of the time, not hidden in a database where mistakes can be lurking that I forgot to update, etc. Also it always crashes on my computer and I haven't invested time to fix whatever is my problem.

But if you start using a spreadsheet, you will become the master of your formula, and everything will be transparent to you and you will notice errors easily that people using hydrobuddy may not see. The guy who made the hydrobuddy program did a fantastic favor and good job, but you will understand what you are doing much better if you make the spreadsheet. So this one time, let's see what you are doing in hydrobuddy before my computer freezes up ;) from whatever bug my download or operating system particularly has.

1. Open hydrobuddy.
2. Clear/remove all the substances used.
3. Put sulfuric acid 30% as the only ingredient.
note: check for every ingredient always that it matches what you are really using. For this, S should be 32.695%, and the density should be 1.3 g/mL. Other elements are all zero. The purity input field should say 30% (not 100 the way we are doing it).
4. Add Sulfuric Acid 30% to the formula, and nothing more.
5. Specify the weight of sulfuric acid as 1020 grams
6. specify the volume of the formulation as 100 L
7. Select calculation type: Concentration from WEIGHTS
8. Carry out calculation
9. Click on results tab and look below and read the predicted EC value.

OK
I did it and it says 1020 g 30% H2SO4 = 1000 ppm S with EC = 3.3 mS/cm. Did you try and get this result? If so, and if this is your battery acid concentration you are buying and adding, all verified, It should be all correct thanks to the help of this program.

Now I selected 1020 g because I want 1000 ppm. This was to force this program to tell me accurately what he is using for a conductivity factor for acidified sulfate of sulfuric acid from which he then calculates S. This is a very reasonable appearing answer from the program I think (not verifed, though). You only are in the 100 ppm range, 1000/10, so for 100 ppm making a linear assumption which I'm pretty sure the program does, will be an additional EC of 3.3/10 = 0.33 from 102 grams of sulfuric acid 30% in 100 L. because the density is 1.3, that is 102g/(1.3g/mL) = 78.5 mL of sulfuric acid (not 64.5 mL, but probably you have some other source of sulfate in epsom salt).

So then, 78.5 mL/100L of 30% Sulfuric acid gives an increase of 0.33 mS/cm. If we use the NaCl calibrated meter, according to his hydrobuddy EC for NaCl, we will think we have added 235 ppm of NaCl, but really the S ppm added was only 100 ppm. Play with NaCl in the program to see. Add NaCl to the database, NaCl purity 100% Na=39.34% Cl=60.66 to your ingredient compare the EC it gives for 1000 ppm NaCl to what it gives for 1000 ppm S from sulfuric acid.

The above example uses hydrobuddy's EC estimates (not mine from the chemical handbook, but his wherever his reference) for sulfur and NaCl to show you that when you add 100 ppm of S using sulfuric acid, your NaCl calibrated meter will tell you you have added 235 ppm of NaCl. But you are just reading it as 235 ppm. Study this example and I think you will clear it all up as to why the high readings appear! (i.e., they are artifacts of the calibration). If you calibrate it for S in sulfuric acid in a range it can handle, you can then use it to talk about ppm S. But for now you are using a different calibration, which is a decent average, but there will be some thing much more conductive like sulfuric acid and other things less conductive than NaCl like MKP. The general idea is the ppm from the meter is a clue as to the strength, but a very crude estimate for these issues.

Now for the future list, you must try to get an EC meter for these types of recipes that you want to balance by trial and error. The ppm calibrated meter is ok if you don't mix your own recipe, but if you mix and improve your own recipe, it is a great waste of time unless you are paid for cryptanalysis! (deciphering secret agents jobs)

This post was edited by PupillaCharites on Thu, Jan 23, 14 at 16:08

It's more clear now. Helped me a lot :). If i didn't downloaded hydrobuddy probably i would not do hydroponics by now. I'm sorry to forgot to give Daniel Fernandez credits for this program. Anyone who is interested in mixing his own fertilizer should check his site at http://scienceinhydroponics.com/ very usefull program and very good informations about hydroponics.

Now i see that EC meter is a must for mixing my own nutrients. Watched a tutorial on excel. And made my first spreadsheet, I'm sorry if i harassed you.
Anyway It was nice to meeting you. Many thanks for taking the time to answer my questions, good luck with your project and hope that we can contact again sometime :-)