<a href=showthread.php?s=&postid=9530150#post9530150 target=_blank>Originally posted</a> by rustybucket145
I just don't agree with this.... So if he has a 10 gallon sump you want him to run a 30 - 50 gph pump? Can you say stagnat water and cyano bacteria???
Run as much as your overflow can handle -and- as much as your sump can handle without creating a micro-bubble issue in the display tank.
If you use a Mag 7 you're only going to be getting about 500gph to the tank. After a couple of weeks and the pump (any pump) slimes up a little your gph will drop continuously over the course of a couple of months until you have to remove the pump for cleaning and then your gph will be back up around the 500gph range.
If you go with a smaller pump your gph rate will drop off considerably faster and by the end of a couple of months you will be lucky if it's pumping any water at all. So if your flow's high at the beginning of the two months and low at the end doesn't that average out about right?
My point is, if you start off with the exact gph rate you want, in a couple of weeks you're going to be below that.... a couple more weeks even more below your target, and by the time it's cleaning time you will be lucky to be pumping much water at all.
Of course this is all just my opinion from my personal experiences. Just remember you can always add a ball valve to lower the flow from the pump, but......... they haven't invented one yet that increases the flow from the pump.