FishNoob wrote:
In article ,
says...

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite

is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).


So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone, so
we collected some rocks and tested them. We set aside those that
contained limestone, but there are a couple of great ones (the kids
particularly like the one that looks like a fossil of an alien's head
G), so if we *can* use them...


I keep a small bag of "crushed coral" - i.e. limestone - in each of my
filters. It's to add some alkalinity (carbonate hardness) and buffer pH.
That's because my city water is soft, about 35 ppm (total hardness or
carbonate hardness - the test kit is not clear which it measures). The
crushed coral/ limestone gives me about 80 ppm "hardness" and a pH of
7.1 to 7.3, so I can be confident there will be not pH "crashes" toward
acidity.

Using carbonate in the filter is recommended by several aquarium books
I've read. Using pieces of limestone should be pefectly all right,
unless you want low hardness and acid conditions.

I think that rocks to be avoided are those containing sulphide or
arsenide minerals (pyrite, arsenopyrite...), and perhaps sulphates (gypsum).

I hope you keep having fun with the aquarium!

Steve