Got the overflow box remade and installed the other day. Big thanks to Dave again for rushing that through the shop for me.
Looks like I forgot to turn the light when I took those pics
Anyways the overflow is pretty big but for good reason, one so I have access being that it has to protrude through a wall and the other relates to volume needed for the two pumps. The idea here is rather than running a traditional return pump I run a large return pump direct from the overflow to to the tank for circulation, the head loss here is very minor. Then I run a second smaller return pump from the sump to the overflow. Sort of like an overflow in an overflow or something you might do as a mod to an AIO tank. My reasoning for it is as follows;
- Take advantage of external pumps for circulation without adding an actual closed loop.
- Being able to separate the sump system from the tank without effecting the actual tank flow, good for maintenance and/or future additions or changes.
- Separate control of sump turnover rate.
- Possible gains in efficiency and lower noise levels.
- Possible gains in simplicity and reliability when compared to closed loop.
- Double surface skim effect (water from tank skimmed at high flow, then overflow skimmed at low flow and fed directly into skimmer intake).
- Possible to add variable pump control if later available.
I'm running two pumps just for redundancy, if one fails then I still have circulation. Also being DC pumps I figure someone will release a module for external control with 0-10V so having two pumps will allow alternate flow patterns.