Just thought of another question

Personally I just use 3/4" tubing on my return pump to the top of the tank. If you have PVC pipe at the top you can probably buy a PVC fitting that has a barb fitting for hose on the other side. Just remember to use hose clamps on the tubing (plastic kind in the sump as I found out even the stainless steel hose clamps rust fairly fast in saltwater)