What changes PH levels?

[xplanes]

I have an established tank. 6gal. with a couple barbs, a blue flame tetra and a few otos. I have live plants and the tank has cycled with 0 amonia and nitrite/nitrate The tap PH is 7. What causes the PH to drop to 5 over a one week period?

Thanks,

Lou

 

[Madame_X]

Is there any driftwood in the tank? That could do it...

 

[Techboy]

Chemicals you add to the tank can change the ph. to test if the chemicals are changing the ph take some water and test ph then in the testing vial a cupel of drops of the chemical you wont to test see if the ph in the vial changes over time

 

[xplanes]

Thanks. I can test the 2 gallon bucket I keep water in before changes. It has been treated with Aqua Plus tap water conditioner. We have no driftwood but have an abundance of plants. Algae is growing quite well too.

 

[Terry]

The PH value of your Aquarium water decribes wheather the water reacts acid, neutral or alkaline. The carbonate hardness makes sure that the measured PH value remains stable. The lower the carbonate hardness the more unstable the PH value will be. Check what your KH is. For a PH of 6.5 to 7.5 you want a carbonate hardness of 4dkh-10dkh.
If you carbonate hardness is below 4dkh, that might be why your PH is dropping.

 

[Voodoo Chilli]

Dissolved organics and decomposing matter can cause the pH levels to drop. Weekly water changes and cleaning any dead organic matter (uneaten food, dead fish, decaying plants) will help.

To make sure you're getting an accurate reading of your tap pH, set some water out in an uncovered bucket for 24 hours before testing it.

I would also recommend testing your KH and GH levels, as Terry suggested.

 

[TankGirl]

To make sure you're getting an accurate reading of your tap pH, set some water out in an uncovered bucket for 24 hours before testing it.

I second that. You may be surprised.

 

[xplanes]

Hmmm. KH is about 2 and GH is about 3. Sounds like that is the problem. Now to see why they are low.

Thanks all.