I would say two ac 70s, for some reason I like having a filter on each side of the tank, plus if one breaks or stops working you have a back up. there are a number of good filters out there, aquaclears get good reviews and are cheaper than an fx5 but the fx5 does have more capacity for filtration and a greater flow, wet drys are great for biological filtration but I feel like its not always needed to have so much but it never hurts, right. All depends on your preference, I experimented with a wet dry, it was noisy and I had a few newb problems but I liked its flexibility.