What size pump do I need??

[racinfan83]

I have a 90gal reef tank with a 30 gal 3 chamber sump. Return goes into a filter sock in the first sump chamber where the protein skimmer is. Middle chamber empty except for a bioballs bag, water flows from middle chamber over a filter into the pump chamber. Probably 4' - 5' between pump and outlet (head height) I currently have a Rio 1500gph pump (so it says) on there which is dying. I kinda question how good it was or what it's flow rate was since it was a cheap p.o.s. when we got it. I have 3 of the Marineland 900gph impellers in the tank for flow as well. Looking at getting a Pondmaster Magdrive to replace the pump - but not sure if I need the Mag 9 or the Mag 12? Little help here???

 

[snakeblitz33]

I know that a rio1100 only puts out 200gph at four foot of head. So, a rio 1500 should be right at 375gph.
On a 90g tank, a mag 7 or a mag9.5 would definitely work. A mag 12 in my opinion, might be overdoing it.
A sump is for cleaning and heating your water. Too much flow through your sump and your filtration doesnt have enough time to remove everything. Macroalgae also needs somewhat slower flow rates.