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Thread: Ph Swings, waterchanges etc!

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    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by bluelagoon View Post
    What is your rational for adding crushed coral for an already high KH and PH? Never heard of doing it on those water parameters for discus.
    Hi Merv,

    Just in previous discussion with Don, it was basically just experimental to buffer PH to see if that would reduce swing, with plants back in tank.

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    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by dspeers View Post
    That may be my fault. I indicated that increasing the Kh would reduce the ph swings at night. In addition he indicated that his Kh was 5-6 which is a little low in what I understand is proper Discus range 4-8.

    There are still things about this tank that confuse me or I did not ask but should have. Given that he was able to stabilize the pH I kinda backed off, I can be a little OCD and did not want to be a PITA The biggest puzzle is that to my understanding unless tank circulation is very low or top is tightly sealed or tank design has very small air/water interface or Kh is under ~3.5, pH should not move by ~0.5 without supplemental CO2. Unfortunately none of these situations apply and I am concerned that I am still be missing something.

    1. Why does his mechanical/Carbon filter drop the tap water pH from 8 to 7.5, not particularly important, but weird.
    2. The pH in the aging barrel at 48 hours is 8.5, is that also heated or still substantially colder than the aquarium temp. If colder still supersaturated with CO2. Not that important in this case but the colder the water the higher the risk of "microbubbles"
    3. Did you verify your Kh test results, and more importantly when did you test relative to your water change? If just post water change you do not know if that represents a swing of as low as zero or you added new water with a Kh of 10 to tank water with a Kh of 2. Would be advantageous to test the kH of the aging barrel and tank both just prior to a water change.

    The implications of a wide swing is that your Kh is being consumed by another source of acid, probably NO3. So what is your nitrate level? Given that your pH varied more with day vs night than with water change I would be surprised if your NO3 is high but as mentioned your tank is confusing. If your Kh difference between barrel and tank is low this should also be low, but better to verify. Again testing both the barrel and tank just prior to a water change would be most informative.

    If your Kh variance is low and is indeed 5-6, I agree with Mervin, raising it offers no substantial benefit, but in fairness changing the Kh from 5 or 6 to only 8 should not increase pH by all that much. If your Kh has major swings you have a different problem with a different solution and the plants are a diversion. But, the fact that removing plants fixed the problem should mean this is CO2 and only CO2.
    I've only got a fairly basic understanding of co2 in that, concentrated co2 at night will drop PH, and it will rise back up during the day as the plants consume the co2. Interestingly a few planted tank forums suggest that a swing in PH over several hours does not affect the fish and will not stress them - however this was not in relation to discus so I sort of disregarded that. (This is just from my research).

    I have monitored other tanks/ponds that I have, and my turtle pond stays at a steady PH, regardless of day or night - it has little to no plants as they eat them. It gets all the same water that my discus tank does.

    Hi Don, Nitrates are always at 5, never higher (at the time of testing of course)

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