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EC, PPM, pH meters

10 years ago

EC, PPM, pH meters

Posted topics included in this FAQ are:
Basics of EC
PPM testing--is it necessary?
Looking for a nutrient meter

Basics of EC

Posted by thedude27 (My Page) on Thu, Jan 12, 06 at 16:46


I'm new to hydroponics growing and have a basic question about mixing the nutrient solution. Currently I'm growing some sage in a homemade DWC system and was wondering if I'm mixing the nutrient solution correctly.

When you are mixing to obtain say 1500ppm nutrient solution do you add the 1500ppm on top of the reading of your water without solution? So if I had water that was reading say 500ppm before adding anything would I then add solution to bring the reading to 2000ppm? Or could that provide your plant too much of a certain nutrient (obviously something is in there raising the count).

Also at what point (well water) hardness would you consider using distilled/spring water? For me its not such a big deal since my grow (crop) is small for now, but it would be easier to just use tap water (or filtered tap water).


Posted by: hank_mili Z11 (My Page) on Fri, Jan 13, 06 at 17:40

The PPM in your tap water is the same whether you have a tablespoon or a gallon. The PPM of the solution from the nutrient concentrate will depend on the volume of water you mix with it. Need to keep in mind that PPM is always a calculated value not like EC (electrical conductivity) which is directly measured. This is why many prefer using an EC meter for measuring nutrient concentration versus a TDS (total dissolved solids) meter, which is an EC meter with a calculation algorithm built in. Unless otherwise stated on the label, the calculated PPM of the solution will assume mixing pure water with the concentrate. But to answer your question the final PPM will be additive and 2000 PPM would be correct.

Posted by: thedude27 (My Page) on Sat, Jan 14, 06 at 23:29

Thanks a bunch Hank, that helped a lot :)

I guess I should have gotten the EC meter instead of the PPM but I got a really good deal on a Newport DSPH-3 (dissolved solids/PH) that I couldn't pass up. Although I'd imagine I could just get the conversion formula from the company and reverse the calculation (although I suppose I'd need accurate temperature readings too).

Thanks again

PPM testing--is it necessary? Posted by Luckyleaf 7 TN (My Page) on Sun, Oct 10, 04 at 23:22

Is it necessary to use PPM testing if I will be growing some tomatoes in a bubbler? Also, if you say it is, what should the ranges be for the nutes in the veg stage and the fruit stage? Thanks!


Posted by: AdrianaG AL z7 (My Page) on Thu, Oct 14, 04 at 19:09

Only if you want healthy plants...and the meter you want is an EC meter, not a ppm meter.

Posted by: hank_mili Z11 (My Page) on Sat, Oct 16, 04 at 2:53

Checking your pH and salts concentration of your nutrients is analogous to checking the fluids in your car. You can get away with not doing it but it is not recommended. It's extra work and expense but gives you important information on the condition of your nutrients.

Tomato....6.0 - 6.5...20 - 50......1400 - 3500

Posted by: Luckyleaf 7 TN (My Page) on Sat, Oct 16, 04 at 11:17

How do I get the PPM up to 1400-3500? Just add 2x the recommended dose of the nutes for the plants? The PPM of my water is ~50, so thats a far way to go

Posted by: willard3 (My Page) on Sun, Oct 17, 04 at 9:58

It will make a difference how large your reservoir is to get nutrients up to correct ppm.

Start keeping a log and how much and when to add and change nutrients will become much clearer to you.

PPM and Ph are closely related so you should test and record Ph as well.

Posted by: Luckyleaf 7 TN (My Page) on Sun, Oct 17, 04 at 15:49

Well I'm doing 5 gal bubblers, and I wont have a reservoir. It is usually like a tsp or something per gallon for each nute, but since tomatoes have different needs I would have to do something like a tbsp per gal? general I would have to use more than the recommended dose

Posted by: willard3 (My Page) on Mon, Oct 18, 04 at 8:49

All nutrients are different; all nutrients have different mineral concentrations.

1. Go buy an EC meter

2. add nutrients

3. Measure nutrient concentration

Posted by: Hydro4me z5 IN (My Page) on Tue, Oct 19, 04 at 11:37

Hey there Adriana,

I have the (brand name) Nutrient Meter, but it reads, "442", "KCL", and "uS" (which I believe is micro siemens). I have heard that the 442 is good for testing pond water with fish and plants, and KCL is potassium chloride. I have no clue which one to use for testing my Millennium nutrients. I try to keep the blinking LED's in the middle, but peppers or tomatoes require higher levels.

Any advice from other hydro gardeners? Thanks, Jason

Posted by: willard3 (My Page) on Wed, Oct 20, 04 at 21:25

Most published stuff on hydro is given in ppm.

I have on that has been working fine for 5 yrs.

RE: meters ppm (ec) and ph
Posted by: NLG1 7b-8a (My Page) on Wed, Apr 27, 05 at 18:11

You can find meters for around $30.00. They work, but for how long is the real question. What you want out of a meter.

1: waterproof
2: warranty
3: replaceable probe
4: pH range 1-14 +/- .1
5: ppm range 1-1999

Posted by: willard3 (My Page) on Thu, Apr 28, 05 at 9:20

A good cheap meter is an oxymoron.

You should get a good meter, no matter what it costs. Hydro goes sooooo much better if you know accurately and repeatable the Ph and EC of nutrient solution.

$50/meter is what I paid and it's worth every penny.

Posted by: HydroBotany Indoors (My Page) on Fri, Oct 28, 05 at 18:40

(HydroBotany suggests a double junction (DJ) product). That is the most important thing with hydroponics. A DJ meter handles the environment the best and last the longest. artisan also has a good meter and it can be used continuously if you want it to

RE: meters ppm(ec) and ph
Posted by: hank_mili Z11 (My Page) on Fri, Oct 28, 05 at 21:49

I tend to be biased toward (another product). Very reliable. No problems so far.

RE: Looking for a nutrient meter

Posted by marshallwilson z4 CO (My Page) on Sun, Sep 25, 05 at 9:27

New to hydroponics. Basic ebb and flow system. Using 2 part dry nutrients (from CK). Currently outside, will be moving inside under lights soon.

I'm looking for an inexpensive way to monitor my nutrient level. Hoping for suggestions on meters.

As an alternative; can I just change out the entire solution every 2 weeks (suggestion from the local hydro shop)? I do get a fair amount of evaporation during the 2 week cycle. Should I just top off the nut solution with plain water?




Posted by: propman Z10 CA (My Page) on Sun, Sep 25, 05 at 11:47

I just got a ppm meter for about $35. Before that I just used the recommended dose on the bottle per gallon of water. What I found when I tested the water was way too stong because my water has 150 ppm before I added nutrients. The meter is a good idea.

Here is a link that might be useful: pictures of my lettuce

Posted by: hank_mili Z11 (My Page) on Sat, Oct 22, 05 at 1:03

Hope you have a pH meter or strips. One can calculate ppm but you can only measure pH.

RE: Looking for a nutrient meter
Posted by: HydroBotany Indoors (My Page) on Fri, Oct 28, 05 at 18:03

Just top it off with plain water.