I have a FOWLR thats a 55 with a 1000GPH return pump and 2 Koralia K3. I've had this tank up for two years and recently I've got some smaller fish. the smaller fish get blown around and they seem to just stay in one spot where the flow might not be as harsh. I've also lost a few to getting stuck in the inky box on my drain. Well I cant get the correct flow with my power heads. I turned the return down to half so thats good, but I tried using 1 Evo1400 and that kept the fish to one side of the tank and now I have a K3 in there and I'm still worried thats too much. I ordered on amazon a evo 425, do you think that alone with the return would be enough? it would be about 16x. I"m just concerned about this 1" porcupine puffer in there. he's not the best swimmer and I don't want it to get tossed around too much. let me know what you think. Also if I shut taht k3 down and just ran the return pump would that be enough movement for tonight till that new PH arrives? I just saw him struggling by that power head and he did a few back flips
