Would having a Hydor Koralia Nano (240-265 gph) AND my stock pump (105 gph) be to much for a Oceanic 8 (about 8 gals) which is going to have mostly softies?
i don't know about overkill. Only thing i would say is they do a great job of moving water but the one i had would rattle a lot. Very irritating. I then switched to koralia 1's.
With softies you should be find with what you are at. I'm persoally upgrading my 500L/h to a Koralia Nano in addition to my HoB refugium sump mainly because i plan to run some SPS at some point and need the additional flow. Particularly with mushrooms you dont want too much flow.