ah that makes sense actually, never thought of those for heaters. okay so there's slots for "HOB" filters hmmmm. Well that opens up some options as well I guess. I'm still maybe leaning toward overflows in each rear corner. A sump of some sort, and a canister filter in series.
retics will outgrow that tank in a year for sure. they are a smaller ray but they have a very long tail. maybe try a hystrix they are smaller also but dont have the really long tail.
I am running 2 ac 110s and a lifeguard fluidized bed filter model 900 on a 240 and I haven't had any problems at all. Overfiltering with rays and discus seems to be the key as well as regular big water changes. I agree, they will outgrow that tank within a year if healthy and eating properly. With three motoros, one leo cross, and a tigrinus I will have to upgrade in a year or so too, my wife just doesn't know it yet.
id just run two jebo 829s the dwell tim is awsome in them making up for the lower gph i added one to my 125 a few months back im more than pleased its awsome for the money good reveiws and did i mention cheap im runing the jebo and 2 hot magnums one with ceramic rings in it as the only media one with ammo carb and in the jebo just the media that came in it my water has never been clearer or healthier im not trying to presure you just dont see the point in buying a expensive filter where all you pay for is the name