Drilling third hole in overflow

[reefman323]

I have 2 overflows both have 2 same
Size holes. I want to run herbie but also returns through overflow so that I don’t have to run plumbing behind the tank. Do you think there is enough room to drill another hole behind these?

 

[MoshJosh]

It would be cutting it close (no pun intended). Just keep in mind the bulkhead width and the silicone in the corner (don't want the bulkheads overlapping and don't want the corner bulkhead sitting on the seam/silicone). Not to sound like that guy, but measure like 100 times and drill once.

 

[reefman323]

It would be cutting it close (no pun intended). Just keep in mind the bulkhead width and the silicone in the corner (don't want the bulkheads overlapping and don't want the corner bulkhead sitting on the seam/silicone). Not to sound like that guy, but measure like 100 times and drill once.

I agree with you. I don’t mind running returns outside behind just would look cleaner if I could
Get a third hole drilled

 

[Kershaw]

I agree with you. I don’t mind running returns outside behind just would look cleaner if I could
Get a third hole drilled

I had a tank like this and was able to drill the back for the returns. Just make sure it’s not tempered.