Just bought a nano skimmer for my 20g QT

[tim the toolman]

Yep. And you just gotta twist the center pin to adjust based on the suction of the filter you run it on. The lower you thread it the more it draws from the top and if it is pulling the cup underwatermyou just turn it back until the skimmer floats and your good. As im sure you noticed it also draws from the bottom which is where the extra pull from the filter is directed as you adjust you top floater.