I've never seen it stated in any instructions anywhere, it just seemed logical to me to have the outlet coming out on the righthand side because the pump is (nearly always) on that side, beats having the tubes crossed. I don't 'spose you could see it without the lexan top though!
, but the furthest off~centre barb is the outlet, it should be on the right side, not left...
CHECK IT SOON!! ,
please!...