I have a 20 gallon tank with a Penguin 125 filter. Ammo. 0 ppm, Nitrite 0 ppm, Nitrate 10 ppm, ph 8.2, and hard water. I can't remember those specs. I had a 2 neon tetras and 10 red plateys. I recently added 4 more neons and a Cori cat. I started losing fish. It started with the baby plateys. Then the neons. I checked and rechecked water specs and nothing. I did however notice the mother red platey looked velvety so I thought maybe there was disease about in the tank. So I started treatment with a product made by Wardley for external parasites, bacteria and fungus. The rest of the neons died, and I now have 6 baby plateys left and now I can't find the mother. The cat seems fine and dandy. It seems I lose one fish a day since this started. Help!!! Oh and yes I removed the carbon from the filter. I have 4 days left of treatment. Also, the other day, about 2 days ago, I noticed white dots on 2 of the plateys, Ich I think. They didn't have these before. What could be going on here?