Hey guys,gonna change out my filter,figure its time to get rid of the 1 that came in my kit. Thinking of going with either the Marineland Emperor Filter System for my 29g or the Marineland Penguin BIO-Wheel Power Filter for it. Need 2 things from you guys.......1- what filter to go with for my 29g tank? 2- will it harm or couse interference with my tank balance if i change out the filter with fish in the tank? also going to be adding a few more fish into the tank tomoro as well as put in the new filter.Any help is greatly thanked,look forward to going shopping tomoro!!