Having a problem with nitrites. 55 gallon, 6 weeks old. Community tank, 
no more than 4 fish added per week. Nitrite levels jumped, yet ammonia 
remained 0. Upped my aeration,put new cartridges of charcoal in the 330 
penguin power filter. No undergravel filter, at the suggestion of the 
salesperson. I also added nitrifying bacteria. Suspecting the lack of 
undergravel filter a bad thing, perhaps it is limiting the growth of 
good bacteria? Placed a nitra-zorb pillow in the penguin, where the 
floss normally goes. Lost 7 fish, including my favorite, a rainbow shark
who rarely hid. Can anyone tell me any other methods to control this 
nitrite problem? Would the introduction of live plants help? I do not 
have too many fish in the tank, nor do I overfeed, so these factors can 
be ruled out. This is the only aquarium I have ever set-up without an 
undergravel filter, I am going back to that system plus power filter in 
future tanks, I really don't want to tear down the 55 and restart. I 
have no 'hospital' or holding tank at this tyme, and would rather 
control the nitrite.
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