And then when your tank is running and you bump into it and make it slightly lower the power will shut off. Ask me how I know.That’s lineloc. Just bend it up so top edge just comes out of the water.
If you do stick with loc line I might glue it in place to prevent sagging. I bought a badly drilled tank and used fittings and hard pipe to raise the over flow level during a power outage.
The hole is at around 15 gallons of water drainage, combined with sump levels for a return pump I think you will need more like a 30 gallon sump if you decide not to use hard pipe returns to raise the level. Otherwise, use a plug in the bulkhead and get a U pipe return that comes over the top edge and will only siphon an inch or two.