i have had a saltwater tank for 2 years and just learned this

Avoid copper by all means.. its a bastard to get rid of traces of it after treatment.. Ive done the lowering of salinity trick before. but with corals might want to take them out of DT for that, due to stress.. fish can handle it though.

 

I used to over stock so bad.. always wanted 1 more fish to add. seeing the new fish attacking existing ones, vice versa, introducing diseases, picking at corals, etc... its a risking thing. Ive had stringrays, eels, angles, tangs, puffers, damsels, triggers, etc.. all have died over 11 years of saltwater experience. once you cross your bio-load cap then bad things can happen.. so keep the fish to a min. and usally everything will pay off in the long run with success..

 

that is a very great idea! way better than bags floating around freaking the guy out