Agreed with Buds, I was trying to be polite hah. H2O2 is the answer with a higher dissolved oxygenation count in the res and the water stirring, you'd be well on your way. Get a res thermometer, keep the temp below 70 if you can. Every degree above 70 increases the conditions that bad bacterium likes and thrives in.
Steps:
-Get H202 and sterilize and clean the entire res, tank, pumps, pipes, drains... anything that touches water.
-Either begin to enrich with H202 or you WILL want some sort of beneficial bacteria in there to take up space from bad bacteria getting a hold on the environment. Indoor grows can be taken over in a matter of a few short days if not taken care of a sterilized properly.
-get airstones or a simple submersible pump to stir the water and nutrients constantly as well.
-cover the top of the res with a lid or panda plastic if you havent already, light and heat from the lamps will increase the temps and give bad fungus a better chance of survival.