Sorry I goofed, I got 2 #3's and 2 #2's. I don't have the tank up and running yet, and I wanted to make sure I had enough because it was such a good deal and I knew the price would go up, so I said get um while their cheap! But after using them I think I'll prob use them all. I'm going to put the #3's on opposite sides facing each other and then the #2's between the two overflows. They will all point slightly up to really get the surface going. 2900 gph total sounds like alot, but the flow is really wide. I set them all up in the bathtub like I was planning in the tank and put a couple little plastic plants from my wife's freshwater tank in the middle to see how it did. I really liked the flow! Not any real push in one direction or the other, just a lot of gentle swaying back and forth (very random) I don't think it will be to much flow, but I have been wrong before, lol. If you put your hand about 6in in front of the pump the water is so dispersed that you can hardly even feel it. I would compare the flow to less than a MJ 600 when your hand is right infront of the output on the Koralias. Also just for kicks I put a couple peices of toilet paper in the water to see what the suction was like into it, and it was very hard to even get them to be sucked towards it at all, just kept pushing away, no real suction going in. This makes me feel even better knowing that things wont get sucked right in to it.