Help with plumbing an external overflow return

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mwbbrown

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Hello,

I have acquired a 20 gallon lagoon style tank that was pre drilled for a modular marine external overflow box. The previous owner drilled it and never got around to setting it up.

He included the bulkhead to fit the holes and what I thought was a return nozzel for loc line but as I'm trying to set it up I think I've got some problems.

The return pump I have outputs a 3/4 inch line, and the largest loc line I can find looks to be that size but requires threading, which this bulkhead doesn't have. the bulkhead is 1 1/2 inch slip. I can't find a black 1 1/2 slip to thread adapter online or a 3/4 inch bulkhead that will fill the larger 1 3/4 inch hole in the tank.

My experience in life tells me if can't find an adapter for what I want to do then I probably am doing the wrong thing. Any advice on how to do this right, assuming I don't mind buying new parts?

PXL_20260711_191241973.jpg PXL_20260711_191246428.jpg PXL_20260711_191253792.jpg
 

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