Tank Design Help

[sphelps]

Originally Posted by Canadian

It doesn't increase the velocity of water flowing over the overflow, it increases the velocity at which surface-bound proteins are removed because only the surface water travels over the overflow instead of half of the flowing water coming from below the surface.

There's a rather succinct example in the link I provided:

Yeap I know what you're getting at but again like I said before theirs obviously a limit to how small the overflow can be. If you compare a 40' overflow to a 4' overflow of course the 40' will work better since water level will be significantly higher above the overflow. What I'm saying is a 20' could clear the oil faster than a 40' depending on flow rate.

Your theory is sound but I don't think the biggest overflow is necessarily the best. If the overflow is too big for the water flow insufficient surface tension could result. I've seen this before. The way I see it is the second overflow is not needed so why waist the space?