[Laith]

This isn't for my planted tank but was wondering if anyone can figure this out...

My African N. multi tank has a KH of 9 and a pH of 7.86.

My tap water has a KH of 13 and I do a 25% waterchange once a week.

I'm curious as to what is lowering my KH? (I also have a coral sand substrate which makes the whole thing even more puzzling!) I do have a couple of Vals and Crypt plants in there and I know that Vals can suck up some carbonate from the water... but this much and this quickly? There's only like 3 or 4 smallish Vals in there.

The reason this is coming up now is that I will be away for a month so no water changes for four weeks. Will the KH keep going down while I'm away? :shock:

 

[ShaneSmith]

If the Vals are splitting the CO3 than yes. If not then maybe. Are the vals growing? And if so how fast? Do you notice a crust on the vals leaves?

 

[Laith]

I actually put the Vals in there only about a week ago to add some green to the tank. They don't seem to be doing much growing for the moment.

 

[ShaneSmith]

If they are not growing much t han i dont think the KH is dropping from them. It must be another cause.

 

[Laith]

Thanks but any idea on what that cause could be?

I just can't figure out what could *lower* KH.... what can strip carbonates out of the water?

Can bacteria do that? :?