Originally Posted by chris stevens
or would I end up overflowing my sump doing this?
Yes. If you have a return pump and it fails, only so much water will fill up your sump. You can test to see how high to fill your sump in the case of a power failure.
You have two pumps and one fails and you have a flood. One outperforms the other and you have a flood. Overflow boxes aren't as good as having a drilled tank. But they're not accidents waiting to happen either. I've never lost a siphon.
Sumps are great because they increase the amount of water in your system so the bigger the better. The biggest you can fit would be ideal. Plus you can hide your heaters, protein skimmer, etc. in your sump.