Koi-lo wrote:

"spiral_72" wrote in message
ups.com...
Limestone does really interesting things to the pH and

hardness of your water. Not good.

===================
It's great for stabilizing PH and for fish that like hard alkaline
water. I have it in all my pools and ponds. Sometimes in my fishtanks
as well. It's not real attractive though.........

It has to be said that this all depends on the fish - if they need hard
water and high pH it's great....I have ocean rock in my Malawi tank but
wouldn't use it in any of the others...but I will say that it looks
attractive in this tank and suits the fish perfectly

Gill