Rockwool problem def.

Discussion in 'Marijuana Plant Problems' started by STLbudz, Apr 2, 2017.


    STLbudz Well-Known Member

    What up guys still tryna get a hang of this rockwool game .. anyway every time I feed my plant the bottom leaves seem to shrivel and yellow , put new growth seems fine every watering it the older leaves wilt n yellow plus I can't solve my phosphorus issue ...? So I been feeding at ph 5.8
    2ml cal mag / 2ml An sensi grow a&b and a little silica blast for ph up strain is purple punch

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    STLbudz Well-Known Member

    Just checked my ph pen it was off by 2 so I was actually putting in 5.6 instead of 5.8 I'll post back to see if this helped

    STLbudz Well-Known Member

    So I've corrected the feeds to 5.9 and ph is calibrated correct .. and the phosphorus lockout seems to be clearing up a bit , but the lower growth seems to shrivel or yellow out as soon as I feed ..? Any input ?

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    JDMase Well-Known Member


    im4satori Well-Known Member

    for now im just guessing

    I think your under feeding across the board
    and I betting your nutrient ratios are out

    lets get some more info and get you straight!
    id been in rockwool forever

    the silica is likely also giving you trouble

    theres a delicate relationship between potassium, calcium and magnesium

    adding silica adds a large amount of k and can easily throw out the balance between these elements
    theres also a relationship between K and N which could also be a smaller factor

    I need some info on the sensi part a&b
    either take a picture of the label of each bottle showing the listed % for each element and post it so I can see it
    or clearly tell me what it says in a way that's easy to understand
    for example

    part A

    and so on
    Last edited: Apr 7, 2017

    STLbudz Well-Known Member

    @im4sato I'll check that tomorrow , have no idea lol ... but yeah I was checking run off and it was 6.3-6.4 I flushed it last week and feed 5.8 this am came out 6.0-6.1 so look like ph is getting better . Stalk is clearing up but have some stripping .. trying to dial this in lol ??? Rockwool lil difficult ??? , all my soil plants are killing it !!!!

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    mjinc Well-Known Member

    What EC or ppm are you feeding your plants?
    STLbudz likes this.

    im4satori Well-Known Member

    that small a ph difference isn't an issue

    if your anywhere from 5.4 to 6.2 your good

    the fact that your ph is rising

    5.8 going in and 6.2 going out is a positive in good..thats what you want

    are you running a closed/recirculating reservoir or an open drain to waste system??

    what that might tell me is your likely feed an appropriate EC/PPM
    you might need to water a little longer duration each time you water
    the longer waterings will bring your RW ph samples down a bit

    but it doesn't explain a nutrient issues or imbalance
    I suspect (since your using silica) you've got in imbalance in the potassium, calcium , magnesium ratios

    when you get the nutrient mix balanced the rockwool is easy enough

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