Water leaking from base of overflow into sump

[Thanos]

I just finished filling my tank last night and still had the pumps off. Water was completely filled in the main tank and at about 8 inches in the overflow which is where I want it for my skimmer. Went to bed and when I woke up, there was an extra 3+ inches of water in the sump and the overflow compartment was almost completely drained, well past the intake. Did a thorough leak inspection around the bulkheads underneath the tank and found nothing. What I'm currently assuming is that the water is getting around the base of the return and intake pipes and internally leaking down into the sump. The pipes themselves were just pushed in, didn't say anything in the assembly directions about sealing or gluing the pipes into the bulkhead. I could try to push them in further but I'm concerned about damaging the tank. Any suggestions?

 

[Timfish]

You can try using a little silicone sealant on the pipes inside the overflow. PVC cement will obviously work but it's permanant.