I am unhappy with my plumbing setup. I bought my setup used and have learned a lot after buying it. I have a vectra L2 for a Aqueon 210 and 40 gallon sump. The pump is reduced down to a 3/4" outlet and when I try to dial it up to get higher flow the pump seems like it is straining. LFS thinks that the problem is it was plumbed with 3/4" so I am wanting to redo it with 1.25" to the tank which as far as I can tell is what it should have been. The problem I see is that the bulkheads are 3/4" barbs coming out, so I want to replace them.
Next problem, attached photo shows how my overflows are. So unless there is a trick I am not aware of I need to use some flex seal tape to seal up the bottom and middle "vents" to the over flow to before I can swap the bulk heads. Is there some other trick for doing this I don't know about?

Next problem, attached photo shows how my overflows are. So unless there is a trick I am not aware of I need to use some flex seal tape to seal up the bottom and middle "vents" to the over flow to before I can swap the bulk heads. Is there some other trick for doing this I don't know about?
