HI, I have a 180 coming to me in about 2 weeks... I am planning on getting two aqua 500 power filters, a underground filter plus a power head. Is this enough filtration? Right now I have 3 red's ranging from 6-8 inches in a 75. I am planning on adding 4 more of that size. I know I could go up to around 9 for the 1 fish per 20 gallon rule but I don't want it to get to crowded so 1 fish per 25 gallons sounds alittle better to me. I want there to be plenty of room for them. What do you think on the filtration?? thanks. Jake