Now I am not 100% accurate about the water, but I think I read on this site before that I would not want to use the water from the tank cause it does not carry anything beneficial. Yes it has nitrates in the water but as long as the water from your tap is treated with no chlorine in it I would not use the water. The filter with established media and subtracts from existing tank is a must. With that said still monitor the tank cause you might get a small ammonia bloom.