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Thread: EC and PH Stability

  1. #1

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    Default EC and PH Stability

    I run a 4 pot DWC system. 4 pots and a resivor.
    It hold in total between 35 and 40 liters in total. I have completed multiple successful grows with decent yields.

    My problem is that once the plants get to a certain size 5 or six weeks into veg. My EC drops very quickly. Which also plays havoc with my pH.

    Example res change on Monday night. EC at 0.9 pH 6.0 (my base water has an EC of 0)
    EC after 24 hrs. Is 0.6 and PH is 5.0
    Normally the answer is EC is too low raise EC.

    I'm at max EC as I get slight nuet burn on all 4 plants at 0.9

    I believe that my problem is that the volume of nutrient solution in my system is too small and this causes the fluctuations.

    Current resivor holds about 8 liters if I change this to a resivor to one that would hold 50 or 60 liters I should have a more stable system?

    Am I missing anything?
    I am using GH Flora trio with a taste of cal mag. My plants look super healthy I have no complaints about my end product I just feel that the wide EC And PH swings might be stressing the plants.

    Thanks for any feedback in advance.




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  3. #2

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    Quote Originally Posted by Rollingstones View Post
    I run a 4 pot DWC system. 4 pots and a resivor.
    It hold in total between 35 and 40 liters in total. I have completed multiple successful grows with decent yields.

    My problem is that once the plants get to a certain size 5 or six weeks into veg. My EC drops very quickly. Which also plays havoc with my pH.

    Example res change on Monday night. EC at 0.9 pH 6.0 (my base water has an EC of 0)
    EC after 24 hrs. Is 0.6 and PH is 5.0
    Normally the answer is EC is too low raise EC.

    I'm at max EC as I get slight nuet burn on all 4 plants at 0.9

    I believe that my problem is that the volume of nutrient solution in my system is too small and this causes the fluctuations.

    Current resivor holds about 8 liters if I change this to a resivor to one that would hold 50 or 60 liters I should have a more stable system?

    Am I missing anything?
    I am using GH Flora trio with a taste of cal mag. My plants look super healthy I have no complaints about my end product I just feel that the wide EC And PH swings might be stressing the plants.

    Thanks for any feedback in advance.




    Sent from my ELE-L09 using Tapatalk
    Think your bang on the money mate. I started a run to waste system in a 25L bucket and was forever having to adjust cos of temps and evaporation. I then upgraded to a 60L res and its a lot more stable. Obviously DWC is different from run to waste but I reckon more water in the res is better for stability.

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  5. #3

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    Can't remember the numbers but with dwc there's a minimum res volume per kw of hps (or equivalent) lighting to keep things stable. Bigger than that doesn't hurt the plants but it's more of a pain to fill/change the res. If you visualise a box that fills your floor space and is the same height as your res/buckets, that's a large res and no height lost. Known as a tubbler.

    5 or 6 weeks in is usually when they start stretching. I used to think that leaf tip discolouration was a sign of burning. When thinking about it, high ec during week 1, no burning. Same ec week 5 or 6 and signs of burning? Now I believe that it's a sign of slight defs while they grow so rapidly. I'm not going to do anything about that as I already know that they can yield well with discoloured leaf tips.

    I've only used GH Micro and Bloom for over 10 years and have never bothered with calmag until trying coco. Not even with RO water.

    ime, there is a wide range of acceptable ec and pH. I prefer higher ec for reasons of stability. Yield chasers usually go for 'less is more'. Lower ec probably does yield more...until the ec is too low. Defs happen which can cause toxicity of other elements and the pH can swing like crazy. Each to their own. I prefer to get 90% to 95% of 'maximum yield' every time rather than risk a poor yield while trying for 100%.

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  7. #4

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    Thanks for the advice. I just replaced my resivor that held 6 or 7 liters to a 60 Litre Waste / Fresh Water Tank for a motor home. Its long and shallow takes up most of the floor. Doubled the capacity from 35 ltrs to 70 ltrs. I run a 600w led. I can see it makes logic with the minimum volume of DWC should be proportional to the Watts.

    I must research it further but I expect to see a greater level of stability going forward.

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