speaking of tanks clogging... the weirdest "failure" I've ever seen was last year. I had a diver who at some point during the dive gave the OOA sign and wanted to share air. So I gave him my reg.
I took his reg and purged it, air came out.
I looked at his SPG, there was more than enough air in the tank.
I didn't get it at all... I tried to give him back his reg to try it again and he refused and gave the sign to abort the dive.
Once on the surface he said that the regulator was breathing really wet and when he went head down just before he gave me the OOA sign all he got out of the reg was water.
It seemed ok when we tried it again so we were pretty puzzled, until we took the reg off and turned the tank upside down and opened the valve.... water sprayed out in a jet for several seconds, like a fire extinguisher. The tank must have had several litres of water in it.
And it was pretty gross too, tbh. I'm happy he was the one who ended up swallowing a mouth full of that water and not me. It was hard to find the guilty party too.... The operator didn't know who had rented that particular tank last and since they fill their tanks 3 at a time nobody noticed that it was empty.
R..