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High PH difts need advise

Discussion in 'Aeroponics' started by Triggertrevor, Sep 19, 2011.

  1. #1 Triggertrevor, Sep 19, 2011
    Strain = Unsure (blues) that all I know
    How many plants = 2
    Veg or flower = Now 1 day in flower / 24 days in veg
    Indoor or out = indoor
    Soil or hydro = hydro x2 205 gti nft trays
    Res size = 20ltr each
    Medium = 3" rockwool cubes
    Light = 600w hps in parabolic shade
    Room temp = 25.7c - 26.3c lights on 21.5c lights off
    Humidity = 50% - 55% lights on 60% - 65% lights off
    Res ph = 5.7 - 6.3 depending on drift
    Pests = only kids (no pests)
    Nutrients = microbial,Dutch pro take root, Dutch pro soft water grow A&B,dutchpro soft water bloom A&B from tomorrow
    Ec levels = first 10 days ec1 after speaking to Peter from Dutch pro ec level now 2
    Room size 1.5m x 1.5m x 1.8m

    Hi all need a little advise here please.

    You have seen all my info above......... Now over the last few days i've been getting high ph drifts from say ph 5.8 upto ph 6.7 with 12hrs. (plants are looking great by the way)
    Can i just say that both trays are acting the same with the same ph dift within .1-.2 of each other.
    My ec levels have been bang on and haven't moved at ec2.
    Both my nft trays are looking nice and clean with no salt makings at all and i've changed the res every week since i started.
    Plenty of roots on the spreader mat and now in the res but there all lovely and white.
    I wont be on flower nutrients till tomorrow morning so i dont know if that will make a difference after i change the res we'll see.
    The plants do seem to be drinking half the res within a fews days so there thirsty.

    Now just a theory............could it be that my res size is a little too small and thats why i'm getting a steep swing on my ph.???
    Was thinking of setting up a header tank to auto top up when needed but i wasn't sure what ph and ec levels to set the header tank to so that when the header water mixes with the tray water i can still keep the ph and ec inline.

    Thanks all for reading i hope some of you guys and gals out there maybe be able to offer some good advise.:eek:
     
  2. #2 Hank Alvarez, Sep 22, 2011
    Triggertrevor: I had just the opposite problem with pH swinging down when they started to flower, not up, and I panicked. My teacher at the time said to watch my plants, look for any signs of stress, (There was none), correct the pH back to 5.8 and not to worry. I did and you should see them now. I would suggest the same for you. Hank
     
  3. #3 Potreaux, Sep 28, 2011
    Rockwool is basic and has a tendency to raise the pH. After so long in veg and the problem starting now I can't be certain. Have you recently transplanted to larger rockwool slabs? If so, did you give them a good pre-soak? If both are true, then the rockwool is the culprit.
     
  4. #4 Hank Alvarez, Sep 29, 2011
    Last edited by a moderator: Sep 29, 2011
    Potreaux: I mostly grow with Hydroton but I don't like the residue that you always seem to get no matter how well you rinse it. I tried rock wool and I still have some cubes left. I didn't have as much trouble with pH swings as most people apparently do because I neutralized them to start out, but I did get a lot of mold growing on top until I covered them with white plastic net pot caps. One of the students buries his cubes in about a half inch of Hydroton on top to avoid the mold.

    One of our instructors at school says the tendency to form mold is the nature of the beast and is pretty much unavoidable unless you cover them, but he credited the pH swings to being caused by their ability to absorb salts from your nutes. He advised frequently flushing them in between feedings, (nutes changes), with pH balanced water to minimize the problem. Something to think about? Are you flushing? He suggested more frequent flushes were necessary with rock wool.

    I'm looking for anther growing medium that's clean but doesn't cause a lot of other problems. Please let us know how you solve your problem. Hank
     

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