I purchased a K4 from a friend for my 55 gallon. I really like how it flows but I think it might be too much flow for my 55. Should I give it back or switch to a 2 or 3? Do you think the 4 is too much?
I agree depends on what you want to keep I have a K4 and a K3 in my 55 in addition to my return pump (450gph) and my canister (200gph) for about 2400gph. I have a mix of softies, SPS, and LPS corals in my tank.
I also have a 228 Powersweep (has built in wavemaker) and my return from my sump is pretty strong as well. I removed the 228 and placed in the #4 and it was still blowing stuff everywhere. I kept repositioning it and it was still too strong. I really like how it works. But it made my corals close up. I might try and get a #3 later on. I have ample flow now so it is not a problem. I just heard good things about the Koralias and I got a good deal on it.
You might try it again your corals will close up initially but should get used to the the extra flow after a day or two. I have far more flow in my 55 than you have (about 2400gph) and even my softys stay open except for some xenia that migrated to a spot right in front of my K3 about 8" away. I have a mine mounted on the sides blowing across the tank towards the opposite corner, if you are trying to go from back to front it will probably be too much.
I have a k4 in my 55 on the right wall at the top, pointed across the tank lengthwise and it works awesome. It took me like 30 minutes to position it just right, and my corals had to get used to it for a few hours, but now I love it
I am still running it. It took a little adjusting to find the right spot. I placed it higher up blowing across the tank. It is working out great. I have great flow now. Everything is doing good. I think it will stay.
k4 is fine for a 55g. I have a 1400gph maxi-mod which is everybit as powerful as a K4 plus a K1 and sump return in my 30g and everything easily tolerates it, even the low flow acan lords.