What rocks will help harden my water ?

"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

Neither slate nor granite (of conventional compositions) will harden your
water. Calcium is typically seen as a white mineral in rocks, corals,
shells, bones etc.

A quick list of water hardeners : argonite, dolomite, limestone, coral
and tufa stone (all of these as stones or ground into a substrate), utah
ice and petrified wood (calcified). I've never seen the colour of
argonite. Utah Ice is almost transparent but I've been told that it only
affects gH and not kH. Dolomite can have a greyish hue. Petrified wood
is shades of brown and would look very attractive, but is somewhat
expensive. There are also chemical methods to harden water (which I have
no recommendations to make), or you can pre-harden the water in a storage
tank, or use the choosen minerals in a sump filter to continuously harden
the water. I'm not aware of any other options. hth

NetMax