Why is PH rising ? - The Planted Tank Forum
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post #1 of 5 (permalink) Old 08-29-2019, 02:05 AM Thread Starter
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Why is PH rising ?

I have a recently set up tank that the pH is climbing to 8.2 within 24 hours of adding water. Water from well goes in at pH of 7.8

I tried adding Seachem pH buffer, got tank water to 7.2 and 24 hours later it was up to 8.0.

Here are the specs:

Newly set up 9gal Fluval Flex, stock filter and lighting. Added some mature filter media from a friends tank to filter. Set up 10 days ago.

Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 0ppm
I don’t have gh/kh test yet, but water is typically pretty hard due to area having limestone

Well water ph from tap: 7.8 pH

Substrate: CaribSea naturals sand
Hardscape: Driftwood with slate base (slate under substrate)
Plants: Java fern, moss, subwassertang, Buce...
No fertilizers or CO2 used.
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post #2 of 5 (permalink) Old 08-29-2019, 09:07 AM
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My guess is this is due to CO2 off-gassing. In which case I believe it is not actually problematic, as most people with pressurized CO2 aim for a pH drop of 1 during the day, and it is not affecting pH in a way that is meaningful to fish.

But I hope somebody with more experience with this weighs in!
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post #3 of 5 (permalink) Old 08-29-2019, 12:12 PM
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This might be due to Co2 off gassing. It is not so problematic as pressurised Co2 can result in PH drop by 1.
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post #4 of 5 (permalink) Old 08-29-2019, 12:46 PM
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CO2 can build up in the tap = lower pH.

As it offgasses (after adding it to the tank) the pH will typically rise, leveling off at your true pH value.

Don't sweat over it....


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post #5 of 5 (permalink) Old 08-29-2019, 02:02 PM
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1) Take a glass of tap water and measure KH and pH. Let it sit out for a day or two (can be accelerated by aerating it) and then measure again.

2) What is the KH before and after a water change?

3) How are you measuring pH (test kit)?
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