Hello all! My fiancé has a 90 gallon flow through breeding system, a 75 gallon tank, 65 gallon tank, 2 18 gallon tubs, 2 10 gallon quarentine tanks, and a 15 gallon tank. He had gotten this new stuff 'smart start', and on the bottle it said to use after each water change. He started using it on the 90 gallon flow through system and the 65 gallon tank. Long story short they got a bacterial infection and about 85% of the fish that were in those two systems. We took the remaining fish and put them in a 30 gallon tank and treated them (way more cost effective to do this way than treating all 90 gallons and all 65 gallons). All the other tanks that this stuff wasn't used on are fine, no death no nothing in them. So we are linking it to that stuff, but no proof for it. After moving all the fish, we drained the 90 gallon system, there seems to be little 'worms' in the tanks. They were green when tanks had water and are brown now that they are dried out. The 65 gallon tank has live plants so we didn't drain it, but have not had filter running and we have been doing 50-60% water changes on it. I guess this is kinda jumpy but just trying to get all info out there before I ask my questions... Which are: would the bacteria live in the 65 gallon with no fish in it? Should filter be running? How long can the bacteria live in a dry tank? How long should we leave them dry? Should we clean tanks and get all brown worms out before refilling the 90 gallon system? Thanks soo much for any and all help. My fiancé is the kinda guy who is just giving up because of all the death, so I am trying to get as many answers as I can... Thanks again :-}