Question about a HOB refugium flow

[Davidb6]

I have a small HOB refugium with poor return water flow. I have to continually reduce the pump volume to avoid overflow. Checked the return line and its clean…no obstructions.

My (U shaped) return plumbing extends to just off the bottom of the refugium to an adjustable directional return in the tank. I see the new CPR hob refugiums simply have straight plumbing (not U shaped) from the refug back into the tank.

Anybody have any experience with a hob refugium with a slow return….how to fix.

I've considered -

1, Raise the refug to get help from gravity (would be difficult)
2, Increase the return plumbing size (came from mfg this way)
3, Eliminate the U plumbing and replace with straight (could get debris in tank)
4, ???

[Davidb6]

bump

Looks like most older HOB refug had the U shaped return, here's a new refug with no return plumbing other than a straight pipe.

http://aquarium-supply.biz/v/vspfile...03401_LG_2.jpg