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Thread: Why is PH falling in DWC??

  1. #1

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    Default Answered: Why is PH falling in DWC??

    The PH in my DWC System keeps falling by about 0.6-0.8 per day was wondering why and what this means?? also nutrients is rising by about 0.1ec everyday without adding more nutrients


    I think it means the plants have too much nutrients and they are comming off plants and lowering ph and increasing ec would this be right.


    currently in week4 flowering ec being kept below 1.2, ph 5.8-6.1 but drops everyday

  2. "Yes!
    I know your EC is "below 1.2" but not the exact number.
    1.2 is usually ok in DWC unless you have a hungry plant, in which case, 1.4 may make all the difference.

    The reason to increase the EC is that for the EC to rise, the rise has to come from within the plants roots.
    A plant cannot leech nutrients in this way if the EC of the water is higher than the EC of the plants internals. So by increasing the EC of the nutes, it forces the plant to take in nutrition rather than leech it.
    You have to still be careful, too high and you will still get burn but if you have burn already, it is possible this burn was down to low EC rather than high EC.
    It wouldnt be the first time nute burn has been misdiagnosed.

    The thing is, put it this way.
    You have tried other ways of solving, increasing your EC to around 1.4 won't hurt that much if I am wrong.
    Good lcuk fella. W"


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  4. #2
    Upton Guest

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    Ec up, PH down = less nutrients needed, add plain water
    Ec down, PH up = she needs more nutrients
    Ec stable, PH up = All good

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  6. #3

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    *This is assuming the water level is remaining more or less the same*

    A falling ph with a rising EC is not the time to start adding just water.
    I will explain why.
    Your plants roots sort of have their own internal EC, which will be different from that of the water/nute solution.
    So if the plants internal EC is LOWER than the solutions, the plant will absorb nutrients along with water.
    If the plants roots however have a higher EC than the nute solution, they will leech nutrients and raise your nute EC.

    So, if you have a static water level, with a rising EC, raise your nute EC.

    If your water level is dropping and the EC is rising, this is when you need to add water to the nute solution.

    This has not looked at the ph.

    If your ph is falling in DWC, it generally means your EC is too low (as above).

    There is a complication however and that is your air quality.
    When pumping air into a DWC bucket, you are pumping in Oxygen but also CO2. The addition of CO2 to water in this way is exactly the same process responsible for acid rain. (Power stations pumping CO2 into the air, which goes into clouds and hey presto, acid rain".

    So, if you are in a city, with high levels of CO2, this may be the cause of falling ph.
    A res change, maybe even twice usually sorts this out.

    So, the solution to this depends on your water levels.
    W
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  8. #4
    Upton Guest

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    Hi Woody...

    At the moment my pH is dropping but the EC is stable. On last weeks res change I added pre-mixed nutes that had been happily bubbling away in a 60ltr bin for a few days, the EC was stable 1.4. A few hours after adding the feed to the res the EC had increased to 1.6 and stayed that way all week. I had suspected that the roots were effecting things and your detailed response helps me understand my plant a little better.

    Thanks for sharing Woody and sorry for hijacking the thread Wonin

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  10. #5

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    Quote Originally Posted by Woody J View Post
    *This is assuming the water level is remaining more or less the same*

    A falling ph with a rising EC is not the time to start adding just water.
    I will explain why.
    Your plants roots sort of have their own internal EC, which will be different from that of the water/nute solution.
    So if the plants internal EC is LOWER than the solutions, the plant will absorb nutrients along with water.
    If the plants roots however have a higher EC than the nute solution, they will leech nutrients and raise your nute EC.

    So, if you have a static water level, with a rising EC, raise your nute EC.

    If your water level is dropping and the EC is rising, this is when you need to add water to the nute solution.

    This has not looked at the ph.

    If your ph is falling in DWC, it generally means your EC is too low (as above).

    There is a complication however and that is your air quality.
    When pumping air into a DWC bucket, you are pumping in Oxygen but also CO2. The addition of CO2 to water in this way is exactly the same process responsible for acid rain. (Power stations pumping CO2 into the air, which goes into clouds and hey presto, acid rain".

    So, if you are in a city, with high levels of CO2, this may be the cause of falling ph.
    A res change, maybe even twice usually sorts this out.

    So, the solution to this depends on your water levels.
    W

    thanks for the info woody!!!

    my water levels are staying pretty level and the ec is rising and ph is falling so what are you saying i should add more nutrients and increase the ec??? even though the plants were badly burnt (leaves bad with nutrient burn).

    last week i put fresh water in ec was 0.4 and didnt add any nutrients, gradually over about 5 or 6 days the ec rose again to 1.2 from 0.4!!!! i was trying to flush all the nutrients outa them, mostly gone now
    Last edited by wonin; 04-12-12 at 06:00 PM.

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  12. #6

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    im a bit confused so ur saying in dwc;

    falling ph and rising ec = add more nutrients??

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  14. #7
    Talpa Guest

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    Have you checked your meter? When was the last time you checked the calibration of your PH and EC meter?

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    Quote Originally Posted by Talpa View Post
    Have you checked your meter? When was the last time you checked the calibration of your PH and EC meter?

    aye the meter is dead on i must have nutrient burned them couple of weeks ago and ever since ph keeps falling and ec rising but think they are sorted now hopefully

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    a stab in the dark here, maybe the buffers in the nutes are taking ph down if you havent let everything settle before you checked it

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    The key to answering this problem is the water levels.

    I have not seen mention of what is happening to the water level.

    The key things to look at are obviously the EC & ph but what is happening to the water level in conjunction with the other factors tell you how to resolve.

    If the water level is falling and your EC is climbing but ph falling, this could be simply that the plant is drinking more than it is eating so to speak. There are other posabilities but if that water level is remaining static with these symptoms, the plant is leeching nutrients back to the water so the EC needs to be increased.

    If you think through what is happening, it may become obvious.

    The worse case if a static water level, static or climbing EC and a falling ph.
    If you have this, it is probable that the issue is too much CO2 going into the water, so a res change will be needed.

    I may try to write a thread detailing how to deal with these vagaries.
    W

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  22. #11
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    Great info woody man, nice......

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  24. #12

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    Quote Originally Posted by Woody J View Post
    The key to answering this problem is the water levels.

    I have not seen mention of what is happening to the water level.

    The key things to look at are obviously the EC & ph but what is happening to the water level in conjunction with the other factors tell you how to resolve.

    If the water level is falling and your EC is climbing but ph falling, this could be simply that the plant is drinking more than it is eating so to speak. There are other posabilities but if that water level is remaining static with these symptoms, the plant is leeching nutrients back to the water so the EC needs to be increased.

    If you think through what is happening, it may become obvious.

    The worse case if a static water level, static or climbing EC and a falling ph.
    If you have this, it is probable that the issue is too much CO2 going into the water, so a res change will be needed.

    I may try to write a thread detailing how to deal with these vagaries.
    W

    cheers woody sorry i thought i mentioned yes the water level is pretty static not moving too much with a falling ph and rising ec, so r u telling me this means the plants need more nutrients???????????

    so i actually need to rise the ec level??

    .....as i said before i was keeping the ec low on purpose cuz they had bad nutrient burn but ive done 2 res changes since and think they ready to get a shit load of nutrients in2 them

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    Yes!
    I know your EC is "below 1.2" but not the exact number.
    1.2 is usually ok in DWC unless you have a hungry plant, in which case, 1.4 may make all the difference.

    The reason to increase the EC is that for the EC to rise, the rise has to come from within the plants roots.
    A plant cannot leech nutrients in this way if the EC of the water is higher than the EC of the plants internals. So by increasing the EC of the nutes, it forces the plant to take in nutrition rather than leech it.
    You have to still be careful, too high and you will still get burn but if you have burn already, it is possible this burn was down to low EC rather than high EC.
    It wouldnt be the first time nute burn has been misdiagnosed.

    The thing is, put it this way.
    You have tried other ways of solving, increasing your EC to around 1.4 won't hurt that much if I am wrong.
    Good lcuk fella. W

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    fuckin hell!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!

    haha never knew u cud get nutrient burn from too low ec that may be what happened cheers woody ill bump it up to 1.4

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  30. #15
    Upton Guest

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    My plant is drinking about 4ltrs a day, the EC has been stable at 1.4 but the pH has been dropping by 0.5 a day. Yesterday, I decided to add some Epsom salts to the 28ltr res. This raised the EC from 1.4 to 1.6, the pH was 6.0. Today I checked the pH and EC and was shocked to see that neither had budged. So, either Epsom salts has magical properties or as Woody said the EC was to low and by feeding the plant more it may help stabilise the pH. I think thats what he said anyway

    Conclusion; I’m upping the EC to 1.6 next week. Btw. My base EC is 0.5

    Great thread by the way.
    Last edited by Upton; 07-12-12 at 11:56 AM.

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  32. #16
    Friday Guest

    Default Why is PH falling in DWC??

    Brilliant bit of Info Woody
    A separate thread detailing this info is a real good idea IMO - defo sticky material

    Cheers again Woody


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    very informative thread.. i think woody's advice should be posted in a sticky entitled "understanding PH/EC movement in DWC" would be really useful to everybody IMO
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  36. #18
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    Well he needs to write a thread dont he, i think its a great bit of info myself.

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    Excellent info Woody, you make it so much easier for us plebs to understand the intracate nature of our favourite plants needs and vagaries .

    Cheers man

    Herb.

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  40. #20
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    Quote Originally Posted by Herbivorous View Post
    Excellent info Woody, you make it so much easier for us plebs to understand the intracate nature of our favourite plants needs and vagaries .

    Cheers man

    Herb.
    You pleb , i love that word , not heard it for years.

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