Very strange indeed. No ozonator as far as I can tell. The tub came with no manuals or papers. It's a 2006 Ventura from Catalina Spas. Can't find any info on this model online. There is a bit of aeration but I turned it off completly today so just heavy currents with no real surface breaking. See if that helps a bit. I'm thinking it's the tub. Something's not right. My friend has a tub and is on the same water supply as I am and he manages fine at 80 TA.