I've been fighting some algae and shocking to high levels for several days. The water is clear now, but it's still burning chlorine at a tremendous rate. In 10 hours, it burned more than 16 ppm.

Reading some old posts, I found this tidbit from Waterbear:

"Ozone will destroy chlorine but will oxidize organics so it's a two edge sword. You will generally have higher chlorine consumption with ozone..."

Could this be why I'm using so much chlorine? If I'm running chlorine instead of bromine - any reason I shouldn't just disconnect the ozonator?

I doubt ozone is responsible for that kind of chlorine loss, but you can always disconnect the ozonator for a while until you are able to hold FC.

It is more likely that you still have algae in the tub. Given the surface area of the plumbing that's not hard to believe.

I wondered that. You think I should try maintaining a couple more days at shock level?

I should also mention that the filter and ozonator have been running the whole time.

Yes, hold the FC level at shock level for a little while yet.

I agree. Ozone will deplete some chlorine (and vice versa) but the amount of chlorine loss you are seeing is most likely still the result of algae activity or crud in the plumbing. Keep shocking until your chlorine is holding (and make sure the tub is not in direct sunlight because you will get chlorine loss from that also!)

I wound up keeping the chlorine another day, cutting back the filter (and ozonator) time, and then finally disconnecting the ozozator.

All seems fine now....

Thanks for the help.