TG you crack me up!
Cougra, I did some testing with FW and yes I saw a little bubbles SG is measurment by weight. the ratio of the density of a substance to the density of some substance (as pure water) taken as a standard when both densities are obtained by weighing in air! which leads me to believe that the dense SW has more time for surface contact with the micro bubbles being generated. Ok don't shoot me on that because I'm thinking outloud here!