Originally Posted by Dav3
Again, just match pump flow after headloss to rated flow of overflow. Get as close as you can or go oversized a bit with the pump and just dial it back a bit.
Just need to keep the air bubbles from building in the tube. Get flow fast enough and it will flush any bubbles out.
I would rather have an over sized overflow box than under sized. If you miscalculate your flow by the gate valve at the return, guess what will happen? If the return is even just slightly more than your overflow you won't notice it and one day when you come home you will find your DT is flooding your floor.
Just remember in CPR overflow box the air pocket that is trapped due to accumulation of air bubbles always stays above the water flowing on the U chamber. Even if you have to set your DT level at max it will not remove that air pocket without using an aqua lifter.