Can someone answer this question real quick?

Discussion in 'Growing Marijuana Indoors' started by HighOnTheHill, Jun 3, 2009.

  1. 2nd indoor grow. First time ever messing with pH =/

    Tested my pH today for the first time and I'm reading bout a 5.5. Don't want to drive an hour to the shop so I just went to petsmart and grabbed some pH increase for a fish tank. Know it's not the best stuff, but it's going to have to work until I got the money go to grab everything at once.

    So I'm just not sure how to do this =/ I just fed my plants (green monster and strawberry haze, 8 total) yesterday and they're still perfectly moist. Not sure if I should just flush out the soil real good and then feed 'em a mild (1/4 strength) nutrient solution with the pH increase in it....

    Or wait until they just need to be watered again (another day or two) and do it then?


    And how much do I use? =/ It's fish tank instructions and uhm this ain't no fish tank. I'm guessing go by the same suggested amount... 5 mL per 10 gallons so .5 mL per gallon? Fish aren't supposed to be hit with a large change in pH either, and you're supposed to change it gradually, so I figure that'd be safe?

    Just thought I'd run those questions by anyone before I try it. My plants are sad, so that makes me sad :( Gonna be doing this in like a half hour if I don't get nothing. Thanks =D
  2. #2 TitaniumFox, Jun 3, 2009
    Last edited by a moderator: Jun 3, 2009
    First, a couple of questions:

    1. Did you test the pH of the water you plan to use before watering the plants? Or did you test the runoff? Also, what is your water source and do you know your ppm before and after adding nutrients?

    2. Are your plants currently showing symptoms of pH imbalance? I would imagine so as you said they are sad.

    3. How old are the plants and are they ready for nutrients? If you have a pH imbalance, the worst possible thing you can do is feed them nutrients they cannot use. You'll further ruin the pH of your medium.

    4. Are you using a reliable pH meter? Is it designed for water or soil? A reliable pH meter for water is hard to find for less than about 60 dollars. A reliable pH meter for soil is much harder to come across. My waterproof pH meter was $125 and I calibrate once a week, at least (overkill, I know... it's never been off by more than .1).


    Check the ingredient in your pH up. It is likely sodium carbonate. The problem with sodium carbonate (soda ash) and sodium bicarbonate (baking soda) is that, in order to stabilize the pH of a solution with a high ppm and low pH, you're going to have to use more of the stuff than your plant really wants.

    Get back to me before you do anything.
  3. #3 HighOnTheHill, Jun 3, 2009
    Last edited by a moderator: Jun 4, 2009
    I'm not testing the water, I'm just testing the soil. Don't have a water test meter, and I was told that my meter won't accurately test the pH of the water. I suppose I can stick it in there and tell you what it reads here in a second, but that's just what I was told

    Yes, they're wilting. Not all of them but about half.

    They're uhm approximately a month from sprouting. They're old enough for nutrients and have been getting them for a little while now. Not sure exactly how long, I didn't write that down =/ But here's a picture:


    This was taken yesterday, they're wilting even more today.

    Edit: Oh, lowered my lights down since then. They were about 12"-14" away, now its more like 4"-5" away, pretty sure that really didn't have anything to do with it. I'm vegging under CFL's and flowering under HPS. Don't have enough light but it's doing fine for now. I've got 62 watts of soft white light and 294 watts of daylight spectrum, for 306 watts total.

    Double Edit: I didn't see the last part of your post. They only had 2 different pH up adjusters and neither had the ingredients listed so I just kinda grabbed one =/ I was going to use baking soda until I read more or less what you said elsewhere. Being as this is only a temporary solution, for maybe a couple weeks, I figure it'd be the less of two evils. If they show a bad reaction to this I'll just flush them out with plain water real good and not give them any nutrients for now.
  4. The soil pH meter may malfunction if you use it to test the water. What type of soil pH meter are you using? I've personally run several run-of-the-mill soil meters through some testing over the years and they all failed with miserable results. I now steer clear of soil pH meters and only resort to soil test kits when absolutely necessary.

    Anyway, wilting is not generally a sign of a pH imbalance. A pH imbalance can manifest itself in a lot of different ways, with the most common being spotted necrosis of the oldest fan blades. The necrosis, which usually appears as brown 'rust' spots, quickly spreads to newer fan blades and finally bud sites.

    One thing I noticed, you have a lot of vertical space for root growth in those cups. When you water, especially with a pot setup like that, you really want to make sure excess water is draining off. I would consider moving to square pots/buckets with a tad bit more horizontal space for the roots.

    Are you sure you aren't overwatering?
  5. I suppose overwatering is a possibility but I've put 6 drainage holes in the bottom and I wait til they're pretty dry.

    My meter is the best one the local nursery had. It seems to take pretty stable readings. Gotta let it sit there for like 5 minutes, but it settles down in the same spot every time I try it. There are SLIGHT differences when I go from plant to plant, or in a different spot in the same one, but its pretty stable.

  6. I have a similar rapitest meter that I paid about 30 dollars for. It doesn't measure fertilizer though, which isn't a big deal, b/c the only thing it does properly is measure soil moisture. My meter consistently gave a neutral pH reading no matter what I did to the soil.

    That meter is probably junk. In fact, any meter that does not require calibration is junk. The most accurate way to gauge the pH of soil is:

    Know the pH of the soil to begin with. Does it have pH buffers, such as dolomite lime?
    Know the pH of the water you are using, before and after nutrients are added. Adjust pH at this point.
    Measure pH of runoff water.

    If you're waiting until they are thoroughly dry before watering, then you should be fine. Is your ventilation and RH dialed in? How about your temperatures? Those would be the next steps I'd look at if the only symptom is wilting.

    Next thing I'd suggest would be root rot.
  7. My temps vary. I'm in a temporary box for now. Don't have any real exhaust fans, just 2 computer fans and a fan out of a space heater. My temps vary from 75 - 85, sometimes they'll go up a little bit higher, but that's usually only when it gets hot in my place because I'm cooking or something.

    Humidity is about 30%

    As far as the junk meter goes, really it's all I got. I haven't even seen a meter that requires caliberation. Even the hydro store only sells the similar type of meters, I haven't seen any digital ones or anything =/ Maybe I just didn't see them.

    In all fairness to the meter, it DOES seem to be working. It orginally was reading an even 7 when I first got the soil. The last time I checked they were between 6 and 6.5. Now I'm reading a 5.5 and it's been about a week since I last checked.

    Yes my medium has buffers:

    SunGro Metro-Mix 300 series

    30-40%horticultural grade vermiculite
    Pine bark
    canadian sphagnum peat moss
    bark ash
    dolomitic limestone
    wetting agent

    I'm using FF Grow Big @ 1/4 strength every watering are about 2-3 days apart. Just whenever the soil dries out.

    As far as root rot goes, I do have roots coming out of the bottom of the cups, but those cups are also placed in another styrofoam cup, I'd think the roots would prune themselves as they're hanging in the air. I'll be transplanting soon enough, but I really don't think its root rot. The roots coming out are a really nice white color, real clean. the tips are turning green as they should be.
  8. #8 HighOnTheHill, Jun 4, 2009
    Last edited by a moderator: Jun 4, 2009
    Keep going with whatever you're going with, but there's still one question I'd like answered =D

    Let's just assume that the pH is @ 5.5 I need to raise it. I have a fish tank ph adjustor that is only a temporary solution for maybe... 2-3 weeks. Is it better for me to attempt to raise the pH for now, or just give them straight water and no nutes for 2-3 weeks (don't think so but...), keep feeding them and don't worry about the pH of them until I get GH pH up?

    I might be able to swing for a digital water pH tester if they're not too pricey when I make my next trip to the hydro shop.

    Edit: I'm still waiting on your final opinion with the direction you were going, I'm just curious about the answer to this as well =D Looking up the symptoms of a low pH now because I don't know what they are. I just seen 'em and stuck the meter in there and went with that right off the bat. Haven't considered any other options until you brought them up. Probably a good thing, I'm overly impulsive.

    Okay so the meter has been sitting in that one cup for about a half hour cuz I forgot to take it out. It's NOW reading 6.0 instead of 5.5. I waited 10 more minutes and checked it again and it's not moving at all. Gonna go ahead and stick it in my nutrient solution. See what that reads off even tho I know it's not meant for it. Can't hurt it anyway.
  9. Oops! I didn't answer your initial question. I've dealt with a lot of pH problems over the years with many different plants.

    We will assume your meter is accurate and the pH of your medium has hit a significantly low 5.5. First off, do not add nutrients to a medium that has a pH imbalance, especially if the imbalance is acidic. To bring the pH up slowly, which as you know is important to both fish and plants, I flush using distilled with 1/2-1 crushed tsp dolomite lime and a pinch of baking soda per 1 gallon. This raises the pH of the water to around 7.8-8.0 while still keeping the ppm low.

    Having a low ppm in the water you're going to use is important b/c the pH in said water is pretty high. When the water makes contact with the soil and nutrients in the soil (assuming you have some), the ppm of the runoff will go up and the pH will buffer upward from your last watering. It takes a lot of practice to correct a pH imbalance, but the key is to bring your pH up slowly over the course of 2-3 waterings. Also, don't overwater your plants when correcting a pH imbalance... you'll make everything worse.

    This is just what I do. There are many different ways to go about altering medium pH. If you already know the pH of your tap water, you could get away with using that instead of distilled.


    Definitely not root rot if they're coming out of the cup healthy. Ready for a transplant though!

    Your meter could very well be working just fine. I would bet against a 40 dollar soil ph meter 10 out of 10 times though. I like 99% odds... =)
  10. Hmmm, keep the receipt for that soil pH meter. Submerging them in water can actually ruin them, haha. If you decide to take it back and go with a liquid pH meter, make sure you don't tell them you used it in pure liquid.. it may void the warranty.

    Your temps are fine and the RH isn't terrible, though raising it 20-30% would be nice. Low RH alone without another problem to exacerbate it will not cause wilting. Honestly, your plants look really good so far. The pictures don't show the wilting that you're experiencing.

    Final suggestion: Move them into bigger containers once they are ready for another watering. Do another dry/wet weight test of the current container to make sure your watering is dialed in perfectly. Make sure your air exchange in the grow space is sufficient as well. :ey:
  11. #11 HighOnTheHill, Jun 4, 2009
    Last edited by a moderator: Jun 4, 2009
    Okay I haven't actually submerged it in water. You're supposed to scrub the damn prod with a brillo pad before you use it, so I didnt think water would hurt it. Guess I won't be trying that.

    My humidity actually varies, I just checked it a second ago and it was around 47%. My whole temp/RH thing varies quite a bit. Depends on the weather outisde too. I'm getting a humidifyer from a buddy of mine just as soon as I go pick it up. He lives next to the hydro shop tho so it'll be then.

    As far as moving them into the final containers, I don't even have them yet =/ I've got six 3 gallon grow bags, but AFTER I purchased those I found out I could acquire some clones, so I thought I'd just keep those ones small and add some more clones to the mix since I'm gonig for a staggard harvest or whatever its called, 1 plant every 5 days or something. Thought I'd do a little SOG and just grow the "baseball bats" so I need to go get some 1-2 gallon grow bags. Most likely 2. Gonna see how many of those I can stuff in there. Aiming for 9-12. I suppose I could just put 'em in the 3 gallon ones anyway and just start flowering soon and veg out the clones separately while they're doing that. But if I can just wait a week or two. that'd be sweet. Figured the root ball inside would just get more dense.

    Edit: Here's a pic I just took, you can see them wilting/drooping more here.


    There ARE some spots on them, you just can't tell in the picture. I had a whole leaf fall off from under the main canopy of the plant, it was pretty bad looking. I would have pulled it off if I would have seen it.
  12. I say transplant them and then neutralize the medium...

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