Baffle question

[andsoitgoes]

Hi all - Just finishing up the design of my sump and with some great help from midknight (and a lot of glass!) I'm pretty much done.

It's a 16.5" high tank, 12w and 24L - I've got the first baffle at about 11", the second is the same, but at the top and then the third at about 10.5"

I have no last piece to place prior to the return that will fit the 10" that I need. I do, however, have a perfect piece that's 9"............ Now, forgive my lack of smarts here, but will that work or am I shooting myself in the foot...?

Any help would be appreciated!!!

Thanks