CichlidFish.com - Fish That Think.

Right now on my 40 gallon i have two aquaclear 200 filters.Should i go ahead and get a magnum canister 250.Or would it be to much if i added a aquaclear 400, in the middle

I think you're OK on filtration in the forty.  I strongly suggest a bigger tank though, and pretty soon.  RD's get pretty massive, and a forty would be pretty tough to keep in good shape.  I think a 75 would be more appropriate for that fish, and easier for you to maintain.