malachite green

[reefnut]

i picked up a bottle to treat my fo for ick.followed the directions on the bottle using only two thirds there dosage.they have a six day treatment and on the last day(today)ive lost nearly all fish.two chromis a foxface and a niger and it seems my last chromis is on his way.my cow and snowflake seem to be fine.still eating and very active.after throwing in some carbon and a 30 percent change with a 20 percent on its way how long will it take the lights(wich were off during treatment)to oxidize the remaining malachite?