Yeah I've been having the sneaking suspicion that the xp3 isn't going to handle the load forever. I do have a magnum250 HOT sitting on my 20gal right now and a marineland emperor400b broken in the closet (needs a new impeller and new biowheels). I think I'd be happiest adding a second xp3, but I'm really big on symmetry

and it'll probably take me a good year to get the extra cash and convince the wife that we do indeed need more filtration on the tank

But yes, in short, I am planning on eventually adding more filtration. I'm also planning on eventually separating the bichirs into a 55g just for the two of them. But that won't happen until I move into a house
I know these fish are going to grow quite a bit, although I've heard of dempseys staying closer to 8" on average, but thats neither here nor there. The ones I'm worried about would be the pictus cats. Half of what I read says 4-6" and half of what I read says 8-10". The other thing is I'm not sure if having 2 or 3 pictus cats on the bottom would stress my bichirs out as somebody mentioned. I think they'd all be ok, but I'm not sure.
I'm not TOO worried about the cats as a cleaning crew, if they're good at it, great, but if not, my sand is easy to clean with a gravel vac
So we'll see, I probably won't be able to make any purchases until next week at least, and then it'll probably be the green terror if I go that route, and a pair of convicts to start breeding in my 20gal.