What is bring down my Ph?

[flukes]

Ok i did a water change with tap water (opps didnt age) and the tap water was 7.2 after ageing it normally comes to 6.8, i did the water change yesterday and today its already dropped to 6.2, what the hell??
What could be doing this??? there is nothing in the filter that would do this, the only thing i can think of is driftwood or those damn rocks i pinched from my mates garden. I am stumped, I dont think that the driftwood or the rocks will cause such a big effect over night.

Cheers
Scott

[gsaqua]

Ph drop can be caused by a lot of things but it won’t drop so drastically if the kh hardness is at the correct levels, so I would suggest testing the kh and buffering it to 125 ppm, kh hardness is the water parameter that determines how well the water will hold its ph levels and not to be confused with general hardness.

George

[flukes]

Yeah iam aware of the value of kh, mine is very low at about 34.6, I ve read something like bicarb soda raising it?? Also ill have to add this at every water change yeah??

Cheers
Scott

[flukes]

Ok i worked out its 1 teaspoon/50 ltrs will increse by 4 degree, only one problem i dont actually have a measuring teaspoon.....opps ill just do it rounded to the water that is ageing and that way if it is more it will mix with the tank water that has had any bicarb.

[Essayons89]

Flukes,

Your kH is a bit low to maintain a stable pH. At 34.6 degrees your kH is around 2dkH. You want to keep above 3-4dkH to avoid crashes in pH.

Since your kH is low you can add kH back through baking soda to the replacement water. Then do 15% changes every other day. The replacement water should have the "ideal" kH level---around 50ppm.

A 1/3 teaspoon per five gallons of water will roughly yield 50ppm which comes out to about 3 degrees.

HTH,
Bryan

[flukes]

iam now with the added water have a kh of 4-5 but it raised my ph, is there anyway i can raise the kh without raising the ph??? I mostly age the water first where it drops but i didnt this time, so maybe i ll give that a go.
Cheers
Scott

[Essayons89]

No. Since pH and kH go hand in hand everytime you alter your kH the pH will rise or fall accordingly. Since you raised your kH the pH will rise. The important thing here is that since your kH is in the 4-5dkH range your pH will be much more stable than it was before.

Stable but "wrong" is far better than unstable and only sometimes "right".

The water parameters in my discus tank are a pH of 7.2 and a kH of 4dkH. I also run peat through the filters. You can lower the pH through peat but the method is kind of a PITA and you need to change the peat out regularly to avoid any wild swings of pH. Filtering through peat shouldn't affect the kH though.

Bryan