Cupramine will definitely kill inverts. A UV will break down Cupramine to a more toxic copper that will likely kill all your fish. I never use my skimmer with cupramine as I have found that a good portion of the treatment was removed. Also try to do it in a qt, as it is easier to get a stable therapeutic level. At first I removed everything from my DT and has used the Cupramine but could not get a steady level. However, I took the fish out and have them in 40 Gallon Breeder QTs and it has been extremely easy to maintain a therapeutic level. Cupramine is highly effective in ridding ich, velvet, etc. Plus it is easily removed. Make sure you get a good test kit also.