Dear Sir,
I did as you asked, and it seems that "cloak", according to my dictionary, can be a method of hiding ones self, a garment or a ruse. I didn't see any mention of air bubbles though. Oh, and if you are using purple up sir?...stop. Cease and desist and cleaning/scraping will be much easier and less frequent, and your pipes, fittings and impellers will not get arterial sclerosis from the build up of marine plaque (coralline algae), also alkalinity will no longer be an issue. I'm really glad we had this time to talk, as if you can't tell, I'm bored out of my mind!