Thanks for the link, quick question though... I don't really get the difference between the "NG" and the "HF" notations. Would NG be ~100% and HF >90% or what's the actual difference?
I have been running that exact airstone for about 2 weeks now in a test setup DWC/bubbler. Working great so far (laying still on the bottom) but can't say much more than that since I've only used it for 2 weeks.