Overflow for a NON drilled tank. Ideas??

I have a 29 gallon NON-drilled glass aquarium that I am trying to connect to my sump. I do not want to empty and drill my tank. I would REALLY like to avoid an overflow box that will clog/break and cause flooding.



Are there options out there?? I've seen a DIY drain pipe over the back that fed into a larger PVC 'container' the had a siphon effect, the issue there being the depth of that pipe would effect the amount of potential flow into the sump during a power outage..



Ideas???



Thank you!

-AA