Thanks for the many good responses. When I first added the crushed coral,
it seemed to work well, but it appears to diminish over time and from Mister
Gardner's response below, it appears that I need to change it every once and
a while. I need to look for coarser crushed gravel than I purchased the
first time. When I added it to my filter it quickly seized the impeller.

From other Q's in the rest of the string, the only fish I now have left are
- 3 red fin tetras
- 1 neon
- 1 female guppy.

The new fished that died were
- 2 hone gouramies
- 1 male guppy

Established fished that died
- 2 cats (don't remember the exact kind, similar to corys)
- 1 dwarf plecostomus
- 3 neons
- 1 beta
- 1 hatchet fish

At this point my plan is to invest in a KH and GH test kit as well as coarse
crushed coral that I can add to the filter.

And from Netmax's reply I will look from the acid source - although I think
I know what it was. We had an automatic fish feeder and it was probably
over feeding the fish. We set it up for a vacation last June and never
turned it off. Since the difficulties I have turned it off and started to
get to know my remaining five fish a little more personally

Thanks,
Mark



"netDenizen" wrote in message
...
Mr. Gardener wrote:
On Sun, 26 Mar 2006 10:18:29 -0500, "J. Bahl"
wrote:


Using crushed coral as the substrate will also work.

I added a mesh bag with a half cup a week ago and today I am pleased
to see that tank has remained at exactly 7.0, which matches my tap
water. The GH and KH have increased some as well, though still in the
soft range. I'm giving myself a while to decide if I want to increase
the amount of crushed coral or hold tight and test again in a few
days. I'm not certain I would like adding it to my substrate until I
am absolutely sure of the amount I want. -- Mister Gardener

I think that the net bag is a good idea long-term, and keep net bags of
crushed coral in my filters. The "hardening" and buffering effect of the
crushed coral seems to diminish over time, and this way it can be replaced
periodically.