Hi what we are doing is using all the predrilled bulk heads from the all glass aquarium to drain to the sump, so we have 2-1 inch
drains and 2-3/4 inch returns which instead of a return we are using for drains to the sump to increase water flow. We were going to take 1 of the 3/4 inches and feed the protein skimmer is that enough? We are also making our own retrun lines from the return pump come from the back of the tank which will be 1&1/4 inch till it get reduced right at the lock line to 3/4. I guess thats where were the confusion is, all the predrilled holes are being use for drains then 1" and 3/4" and we are making our own return to increase flow.