I have the same question for a 125 gallon tank with two Filstar XP3s (no power heads), which I will be setting up when it finally comes in (it's been on order for over three weeks). It also be a planted tank with community fish.
Fishyfanatic, which way to you have the outputs to create the current?
I was thinking of putting an output on one side, then intake, then another output near the center, then the final intake. I was thinking this would create the current. It seems as though most people are using the spray bars, some enlarging the spray bar holes; so, I'm also deciding on spray bar or no spray bar. If I used the spray bar, they would be spraying from back to front??? There are just too many options here; currently I have a 75 gallon with an undergravel and one hang-on-the-back filtration, so this is all new to me too. Do any other folks out there have other arrangements or ideas?