Post
by Kev888 » Mon Oct 17, 2016 3:16 pm
Its a bit hard to tell from the top, the bubbles look similar but a bit fewer and coarser than mine. The one I have (a 2 micron type) gives a shed load of small bubbles that make the water look almost milky, or as if coarse smoke were pouring from the stone, if thats of any use. Apparently some pumps struggle a bit and deep water types, with pressure capability of 0.02MPa or better, have an easier job of getting air through the things.
It isn't hugely critical if using filtered air, though. You can't over-oxygenate the wort and whilst loads of smaller bubbles work faster, a lower number of bigger bubbles will still achieve similar oxygen levels given time - if the amount of foam produced doesn't grow too much for your fermenter, anyway.
BTW, just remembered that when I first got mine it was largely blocked, and boiling didn't help. A soak in percarbonate-based cleaner followed by citric acid seemed to clear it though, so I guess either it was blocked with something organic like grease from handling or else the boiling had blocked it with precipitated minerals. From then on I boiled only in RO water, so haven't tested the theory.
Kev