What you can do to make it eaiser on your fish, in regards to the nitrItes...is add 2 tablespoons of salt (and everytime you do a 50% waterchange add just under one table spoon) just remember that salt doesnt evaporate out of the tank, its only removed by waterchanges, I would keep up with the salt untill your bacteria colony can catch up and start converting it into nitrAtes. What the salt does, is keep the fish from absorbing the nitrItes. the nitrites can still "burn" their gills but it will help them stay alive through this part of the cycle.