Does anyone know how to tune a bak pak cyclone?

I bought a bak pak cyclone and I read that you can increase the amount of scum you collect by tuning it. Does anyone know how to do this?

 

Ask, and ye shall receive:

The quality of foam in the collection cup can be adjusted by sliding the “O” ring up or down. If the foam is too wet, raise the collection cup up by sliding the “O” ring down until the desired wetness is achieved. The base of the collection funnel should be 1/8” below the water surface for optimal performance, but can be adjusted down from this point if the foam is too dry (little to no liquid present) or up if the foam is too wet (clear liquid only in collection cup).

Regards,
Tom