I have seen black marble in headstone shops. They often have scraps you
could breakup. Lots of limestone and dolomites are dark in color. What
part of the world are you in.

Bob
"Earl D Fitzgerald" wrote in message
...
Just use crushed coral or coral sand to harden your water. A good inch or
so should leach enough hardness to make the water desireable for your
fish.
You can use granite stones to create the ground cover for the fish.

Fishboy


"Alan Silver"
wrote in
message ...
Hello,

I'm contemplating a cichlid tank, but have very soft water. My LFS
suggested using a crushed coral substrate and rocks of the sort that you
see in marine tanks as these would help harden the water.

Trouble is, I don't like the look of these rocks. They are too light. I
want something darker to contrast with the fish. I was wondering about
slate or granite (both of which seem to be common decoration for cichlid
tanks).

Anyone know if these rocks will be as effective as hardening the water
as the marine rock ? If not, any other suggestions ?

TIA

--
Alan Silver