Drilling question

[Jack-the-reefer]

I was planning to drill a third hole here so I can have an emergency drain. Is that too many holes, too close together?

[islandVib3s]

4 hours ago, Jack-the-reefer said:

I was planning to drill a third hole here so I can have an emergency drain. Is that too many holes, too close together?

I would say yes. But if it just a emergency,I would maybe go 3/4 with a uniseal instead of another bulkhead. 

[Jack-the-reefer]

I’m mainly worried about the structural integrity having another hole that close. 

[obrien.david.j]

How about a little out of the box option.  If you're not comfortable drilling a 3rd hole so close, on the same pane of glass.  Switch to a different pane.   Can you drill your 3rd hole on the back (or side) of the tank, but still in the overflow box?