Removing sump's dividers
 

My sump is made out 1/4" glass. I wonder if it safe to remover two dividers to have more space. After two dividers remove the space will be 27"lg x 20w x 16"h.

If it's less than 60% full, you're probably ok without bracing. Probably :)

When the system is running the water level is 10" high and when the system is off it 11" high. The total length of the sump is 38" long with 5 dividers. Remove two and left with three for the return section.(no brace)

Garf says it's OK, but they show a tank that size having euro-bracing
I agree with Brad. 11" of water should be safe.
If you're nervous, add a front-back 2 or 3" brace

http://www.garf.org/tank/buildtank.asp

Tank Information:

Material = Glass
Tank Height = 16"
Tank Width = 20"
Tank Length = 27 "
Glass Thickness = 1/4"
Approximate Gallons = 37

Thanks guys.