This is a discussion on How many fish are too many for my 90g? within the Freshwater and Tropical Fish forums, part of the Freshwater Fish and Aquariums category; -->
Awesome....I appreciate the info....I will be sure to nix the Idea of the bala sharks!...
You could get something more appropriate than bala sharks. A school of silver dollars would probably be alright along with one of the plecos and possibly the rainbow sharks. The rainbows are aggressive (which I'm surprised you haven't seen already) so they might not get along with each other or the pleco.
I've heard a lot of complaints about the FX5. The flow rate through the surprisingly small media containers is so high that there isn't a lot of contact time with your media. This makes it good for mechanical filtration but subpar for biological filtration. Plus, an FX5 costs $340. For the same money, you could buy two Marineland Magnum 350 Pro canisters plus two Marineland Emperor 400 power filters. Compare the two options: the Marineland filters would give you 1500 gph total turnover, six Biowheels for massive amounts of biological filtration, and all of the media containers in both canisters and the media baskets in two power filters. The FX5 would give you 925 gph turnover with no Biowheels and less media space. Plus, more smaller filters means more even water flow, insurance if a motor breaks, and you'll be able to move a filter over to a smaller hospital/quarantine tank should you need to without worrying about that tank not being cycled and without a major disruption of the filtration capacity on your main tank. Of course, you don't have to use the Marineland filters; you could substitute AC70's or something for the Emperors and Eheims or smaller Fluvals for the Magnums. I just happen to really like the Biowheels.