300gph rating. not actual flow with any media whatsoever. Since its a HOB (heavy on bypass). full of media...i mean..."cartridges"(lol), will MAYBE get 150gph
the eheim also only does about 150-175
so, that puts you at around 300gph filtration, which is ALMOST 6 cycles in an hour, which is sufficient, especially with a powerhead. however, 300gph powerhead isnt much. a korilia #3 would be better. however, it really depends on how heavy of a stock you plan on keeping. stocking, feeding and many other things play a role in how much you will need.
if you have the spraybar on the eheim, switch it to the jet nozzle, you will get a little flow doing that as well. how do you have the media setup on it? if you were to use some prefilter media and pull out some other media, you will pick up some flow.
i would remove the undergravel filter completely, with cichlids its worthless. i would try it with the filtration you have. if it becomes cloudy or something and theres lots of dirt around. i would just get a 2nd canister, or a whole new canister, you could even add 1 ac110 and remove the top fin. Theres lots of ways to do it.
i have a 75g and i have a rena xp3 and ac110, w/ a korilia #4 powerhead. its not enough, im returning the xp3 and removing the ac110 for a FX5. i paid 190+ tax for the xp3, and 80 for the ac110. The FX5 is 200 shipped on ebay. i will actually be getting money back, by getting twice the gph (rated at 925, get about 500-600gph loaded with bio media).
if i had a 55g and was planning to stock it, i would probably just get the fx5, if you ever upgrade, it will be useful on a bigger tank. You dont have to run it at its full 500-600gph, there are ways to make it not flow near that much. Best bang for your buck imho.
