Sump too small?

[Jms8800]

I bought a 120 gallon tank and I'm getting it all cleaned up and ready for use but I'm concerned that the sump is too small. It's footprint is 23x12.5" I don't know exactly where I should measure for water height though. Any thoughts?

[Jchris896]

Measure once you have it set up to make sure you have enough excess capacity to hold the overflow in the event of a power outage.

[kwroberto]

+1 on checking capacity