Filtration Question

[Ximat]

I am trying to help out a friend in a predicament.

He is taking over two very large aquariums, both approximatly 250-275 gallons. Both are on rock bases with a "cubby" to the side of each. We need to find good filtration options. HOB's are out of the question, sumps are out, canisters are the only thing i can think of. However, due to their size im unsure of what canister filter would be a good option.

Im not sure what specs you need to help me, but please advise.

 

[roka64]

I have This Filter http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3579+17320&pcatid=17320 on my tank.

 

[Ximat]

That one looks promising. I noticed in reding the specs of it, and im sure its the same with others, you cannot place the filter near the water line. What if it is not possible to have the filter below the water line?