Tropical Fish Enthusiasts. Can you help with a number of problems i’m having with my tank please?

An asked:


My husband got a 5ft Jewel tank off someone, we got all new sponges for the filter & new gravel & let it run for a week with no fish in.

Our tank is malawi chicilids, so we had a slate in & made loads of caves for them, after 3 weeks of no problems they then would just start dying for no reason. We lost 5 in 3 days, & beacause they died behind the slate we had to take all that out.

Last week they started with cotton wool disease & mouth rot which we treated with some intrepet No 8 treatment. That worked a treat & even 2 that looked like they were on deaths door cleared up.

My husband noticed that there was no seal on the filter? So got a new part & that fits perfect now, so we thought that had something to do with it.

Yesterday were gobbing on the top for air, so we 50% water change & that worked, but this am they are all gasping. What can it be?

We have tested the water everyother day and the only problem we found was nitrates up, which r slowly dropping now.

HELP!
We replaced the slate with some white stone that we got off someone else. Its very light and when you first put it in it gives off tiny air bubbles.
He has it in his tank with no problems could this be it??

Content