Overflow question

I recently got an overflow box rated for 300gph, it's for my 29gal BC. I was going to build a fuge for my tank and place it on the bottom shelf of my stand. In that location my current return pump would be pumping around 260-270gph. Will this difference in flow rates be ok? I was thinking the overflow would only go as fast as the return pump but I could be wrong. This is my first overflow system so bear with me.

 

The 300GPH is the max water flow it can handle. It will remove the water just as fast as it is pumped in to the tank as long as it is not over 300GPH.

 

Oh, and this is the overflow box I got:

Aquarium Filters: Continuous Siphon Overflow

And my return pump is a Rio 1400 going against roughly 3.3' of head

Taam Rio (Rio+) Powerhead/Pump Details

 

OK, that's what I was thinking but just wanted to double check.

 

Did you buy the tom's aqualifter pump?

 

Yeah, I got the pump too. It was all on sale when Dr. F&S was having their big summer sale.