Ph Test Done, Did We Pass?

Discussion in 'Growing Marijuana Indoors' started by itsmysubaru, Jan 25, 2009.

  1. Hey GC... I'm new to the forums but have been reading up for the past 2 weeks or so. Before applying the FF Grow Big nutes I picked up, I wanted to make sure the Ph level was right for nutrient uptake. Details on the young one are as follows: 21 days since germ, Schulz potting soil (9 month formula, the stuff is crap but it rooted through it for fert and removed what I could find), watered with evap'd Brita when needed. Have FFGB nutes but have yet to feed the little bugger. Good growth so far under 4 daylight 26W CFLs. Suffice to say my imaginary grow has been backwards so far - "Do, then Learn" :eek:

    But I have definitely been learning!

    I decided it was important to test the Ph of not only my basil's water, but also my own drinking water. So off to the local pet store, where I found a suitable range Ph test kit in the aquarium section. True to form, there was a hot girl behind the counter. "No, the snails from the bottom please." The unit I purchased is an API Freshwater kit that measures Ph from 6.0 - 7.6 in nice distinguishable intervals. I figured the freshwater kit would be acceptable, even though salinity may be an issue I don't think it'll throw off the test too much. The marine kit was for a higher Ph range. Please to correct if wrong.

    So the kit is pretty simple, a 5ml test tube full of water and 3 drops of test solution will give you a clear color outcome from bright yellow at > 6.0, through lime, green, minty, aqua, torquoise, and blue at 7.6 or <. I've found that the colors are easily identified and differentiated, and readings turned out to be consistently consistent. ;)

    So on to the test. Up for consideration was standard tap water right from the spigot, fresh Brita filtered water, and stale Brita (approx 48h, for chlorine evap.), and of course soil runoff from my basil sprout. Results yeilded 7.2 for big city tap water, about what I expected. The water from the Brita is more acidic, however, reading 6.2 or lower. The 2-day old Brita came in at 6.0 or a little more. I expected this to be the case from my reading; carbon dioxide is absorbed from the atmosphere, creating carbonic acid. Leaving distilled water out will ultimately result in a lower Ph, too. I've gotta admit, I was a bit worried when testing my runoff water after seeing the acidity of the water going into the soil, but the result was a relief: right at 6.6. I've seen respectable growth thus far with no signs of problems, I'm thinking that's partly due to these acceptable Ph levels. Please let me know if I'm off or misguided here in any way!

    I'm also contemplating cracking open this bottle of FF Grow Big for a 1/4 strength feeding next time, what are your thoughts? Thanks for checking out my thread, I'll have a journal up soon!

    C.N.: Picked up an API Ph test kit, tested tap water (7.2), Brita water (6.2), Brita water at 48h (6.0), and soil runoff (6.6).
  2. If your kit reads in 1/10ths, it sounds like your numbers are good. Not a bad deal, actually.
    Good luck on your grow!
  3. How the hell are you going to check the pH of water with nutrients mixed in when most nutrients turn the water brown or black? Good luck distinguishing yellow from aqua. There is a reason people spend $200+ on pH meters...
  4. Haven't used the nutes yet, so I have yet to encounter that problem... I'll let you know when I (try to) test the runoff.
  5. It sounds like you are using a soil that has ferts in it? If so then sorry but there isn't really solid advice anyone can give from here because we can't know how much fert is actually in the soil at this point.

    If your soil were not pre-ferted then it probably is time to feed, you said 21 days since germ so I presume it has been 14 or more days since it sprouted through the soil, which would be about the right time to give a first feeding at 1/4 strength.
  6. Thanks toastybiz. The Schulz stuff is unfortunate, but my only option for now since my local shop has only FF nutes in stock, and Home Depot has no soil this time of year. The fert 'stats' are .12 (N) - .09 (P) - .07 (K), with .01 sulfer. Not all bad. I figure if I keep an eye on my Ph, and feed conservatively I'll have better luck. The hydro store about 2 hours away has FFOF, that'll be for next time. Again this is a shakedown run for this setup, since I sprouted this sucker before I knew my arse from my mouth, horticulturally speaking. One day at a time!
  7. Gave a first dose of FFGB, at 1/4 strength. Topped the plant as well. Runoff Ph was not affected much, Ph at around 6.6.

    The color of the ferted water was not an issue when testing the runoff, we'll see if this stays true once I up the nutes.

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