This is essentially the way it looks:
The yellow is the tank bottom, below would be into the sump, above is in the overflow box. The grey is the clear PVC you need to buy. The top two black boxes represent the lock line returns.
Ideally you have your gaskets above the glass, on the wetside. BUT because Cadlights has their funky design, I don't think I could get that to work, hence in my pics from yesterday, I mounted them on the dry side. It worked, but not ideal.
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What is leaking on yours, the return only or the drain?