Basically, what hex says, and just to add that a 342 calibration is a weak solution and more suited for testing most tap water. But such hair-splitting accuracy won't play a roll in your hydro need as long as you have a way of telling stronger from weaker on any calibration at all. The actual calculations the stick is giving are really a black box if you start splitting hairs and ... conversions get hairy when you deal with summer vs. winter on top of who's calibrating with what and at how strong and at what temperature. Sticking with EC frees you from ever worrying about ppm conversion factors again, except when helping others wade through the mess ppm has caused. So, you can complicate life with ppms or just use the actual signal of the stick gives, which is EC, and never look back, because the ppm is not what is being measured, it's the EC. The only benefit I see to "ppm meters" is that they are cheaper, but not by much. If you wonder how something that has programmed into it an extra level of conversions can be cheaper that the one that simply gives the raw electrical number, it's because mass produced meters are TDS since tap water is usually measured in ppm, and the guy that started making EC meters makes them in smaller runs. In hydro, there's a case to be made for those using a single brand of powdered fertilizer that ppm is easier to relate to gram readings, but to be honest I have never once seen a single post of someone actually using it for that. If you add up the ppms we are actually interested in, like N, P, K, S, Mg, Ca, Fe, etc., the total won't add up to the ppm on your meter, so why bother? Since you already bought TDS, consider it like a speedometer. Mix the ferts new, and check the reading. The reading is your rough speed limit. No one will give you a ticket for going a little bit faster or slower, but major differences and your plants will need to pull over into the shoulder. If you use EC, though as already noted, you will be able to share your results without everyone degenerating into a ppm vs. EC food-fight! EDIT: Let me add, for your purposes, it is not the NaCl calibration with 342 ppm NaCl that will make a squirrel's ass difference. What you want to make sure is that it is compensated for temperature. A 342 ppm calibration would be extremely inconvenient for me if it were only done at 25 C, and not automatically compensating for temperature ("ATC"). Many of the cheap meters do not have ATC, so watch out since even one degree make a difference in solution measurement. for a typical 10 C temp dif, the uncompensated readings of the same brew will be 20% different - and that becomes a problem! This post was edited by PupillaCharites on Fri, Apr 4, 14 at 15:56

Been watching every thing about lights. Just went and measured my 48 watt red/blue LED. 1 foot square one. It runs about 1000 to 1200 fc at about 6 inches. Hard to measure up close because the LEDs tend to pinpoint the light and give varying readings --up to about 2000fc. Just FWIW, Not sure if my meter is reliable or even what I am doing. Kennyp

Thank you so much, jwv24! I had figured out that the 10X is best used in full sun and it picks up where the meter maxes out on the X1 setting. What I wasn't sure of was which setting is usually used for AV-s. In other words, if I use the X1 setting, and the meter registeres somewhere between 500-1000, does this indicate an adequate amount of light? I assume so because the AV-s want bright light but not direct sun - so I am always using the x1 setting. If I am on the X10 setting and the indicator is barely above 0 (say at 100)...that means we have a 100x10=1000 candles which would be the same as the needle registering at 1000 on the x1 setting - so good. It is my understanding that in order for AV-s to bloom they need a minimum of 500 foot candles ...and ideally between 1000-2000. I am already starting to figure out by the behavior of my AV-s that they probably have been getting too much light where most have been sitting, which is on a stand placed against a south-eastern window where they also receive a few hours of supplemental artificial light, with the light placed about 7-9 inches above them. I wish I was able to lift the light further above the plants but the shelves are not adjustable, so I have reduced the hours instead. Trouble is they also receive some direct afternoon sun, though most of it is filtered by some trees. All in all, it is clear they are getting too much light because as soon as AV-s spend a few weeks there, the crowns start coming in kind of small and tight, stems shorten and leaves curl. I have moved some of them on the lowest shelf of the stand where they don't receive direct light as there is no window at that level...and I have also reduced the artificial light...so we will see if they straighten up. The meter easily registers over 2000 when on the x1 setting. I also have a smaller corner stand right between an eastern and north-eastern vindow (no supplemental light here) but based on what I have noticed, these too seem to be getting more light than they would like. For a few hours, the sun still kind of shines right on them from above, even if it is just morning sun. Being in the South, all summer sun is hot enough sun, I suppose. Things will change though with the colder season coming so my eastern ad south-eastern windows may be just right by the end of September. Thank you again!

I wouldn't even put on a door knob. Have magnets to hold door closed. Paint a simple door the same color as the walls. Some plain unfinished cabinet doors from a big box store or even some close out left over doors they no longer stock. A good handyman can figure out something/ somehow to attach them. It's not like they will be something that needs to be used often.