*** Quoting Nuchumyussel from a message to All ***

Nu> First off, the tank is indeed cycled.

Nu> The methods I have tried are thus:

Nu> 1. Cutting Back on feedings
Nu> 2. Cutting back on the time that the lights are on.
Nu> 3. Adding extra carbon to the filter.
Nu> 4. More frequent water changes. (Currently I'm doing 25% changes every
Nu> other week.)
Nu> 5. Adding "Crystal Clear" drops. They supposedly clump the
bacteria so
Nu> the filter can pick it up.
Nu> 6. Moved to largest fish o a different tank.

Nu> I am deperate will do anything suggested!

Have you checked the various things you have in the tank?  Rocks and stuff
like ¨that?  You may have something that is leaching into the water in a
slow ¨dissolve pattern instead of any actual other problem.  This is common
hwen ¨peope put their own little figurines in there that arent meant for
fishtanks.  ¨Sometimes it kills the fish slowly, sometimes fast (when fast
though, you ¨usually figure out that the new figurine is the culprit).

If you have kids, dont over look them dropping something in there. 
Charlotte, ¨when she was 3, added milk once to our tank and for a short
time, was dropping ¨other things she didnt want to eat in there.
                                       xxcarol

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