Recently I set up my 180g tank (in fact monday it'll be 2 wks) and I've started having problems. I've lost a total of 5 fish all bottom feeders ( 1 gold nugget pleco & 4 four-lined pims.). Here is the issue all my filters came off established tanks 2 xp3 & 1 aquael unimax pro, I also have a surface skimmer and uv sterilizer. I've checked all my water parameters ph 7.0, ammonia 0, nitrite 0, and nitrate 5.0 ppm. All of my fish were transferred from other tanks that have been up and running for about a year, except for the pims. I don't know whats going on I've started to notice a grey film on one of my bluegill and a texas cichlid so I've added more salt to the water and medication. My question or concern is before I got the 180 up and running I spray painted the back of the outside of the tank black. I mask off the tank and cleaned the inside out with plain tap water after I was done. I'm at a lose and I don't want to lose anymore fish.