Plumbing a 125 dual overflow-what size pump?

[Mason]

All right now I'm really confused! I read that the 1.75" drain holes on my dual flow 125AGA will be only 1" after fitting w/ the proper bulkhead and a 1" line can only drain approx, 300 gph. If that is the case, is a T4 (1225 gal/hr) a waste? Seems like I would only need a T2 (650 gal/hr) or possibly 2 T1's (540gal/hr each) if it would be better to use one pump per return line. I am going to use an Oceanic sump which will be plumed for 2 returns if using two pumps is better than one?

 

[Len]

A one inch line will drain over 600 gph of effective flow from my experience. And remember: the pump's rated gph isn't an accurate reflection of what the overflow will actually see because of all the loss from head pressure along the way. I can assure you two 1" overflows will handle at least 2 Velocity T4 pumps @ 6' height, two 90 degree bends (again, from experience).

I have a 120g with a single 1" drain (wish I went with a 1 1/2"). It handles two Iwaki 30's just fine, and each is rated at 750 gph @ 4' head.

Two pumps is better then one. Redundancy is a good safeguard against unexpected failures. A dead pump for unattended for several hours can spell disaster.

HTH. This is just my experiences and opinions, and others may say otherwise

 

[RGibson]

It is much better to used only one pump to run both. A good size would be a MD55RLT IWAKI it is one the best in Iwaki line. About running two pumps if one is not running the water will back flow down to the sump not good.A close loop would be good for a back up pump. RGibson

 

[liquid]

Just as a fyi, check out http://www.reefs.org/library/pumps

Shane