Surprise ozonator - change chemistry?

[Curmudgeon]

I just discovered my hot tub has an ozonator. The owner's manual mentioned it but the sales description did not. It explains the mystery trail of bubbles coming out of one of the floor jets.

Can ozone destroy CYA? I added enough for 20 ppm over a week ago (slow to dissolve of course) but analysis indicates none present now.

Should I add NaBr and begin using bromine as my sanitizer? I'm only filtering two hours per day. Manual says ozonator only works when low speed pumping.

I bought one of the much maligned (primarily by dealers on other discussion sites) Infinity hot tub from Costco. I have been using it for almost four months. I decided it might be worthwhile to add insulation under the tub and on the sides. The tub sits on a ground level deck a few inches above bare dirt.

There is a layer of spray on foam insulation on the back of the tub and most of the plumbing. The pump mounting is sloppy (vibration isolation pads not centered well). There is a stiff plastic sheet under the frame of the tub and pieces of plywood on the frame where the pumps or the woofer (another surprise) sit. I shoved styrofoam packing material (loose and sheets) under the plywood and over the exposed plastic sheet. I taped 1” R-4 blue wall insulation in the side panels and reattached the aluminized bubble wrap over the sides. I left the two pumps clear of added insulation out of concern for overheating them.

Thanks,
Curmudgeon

350 gal Infinity using BBB

 

[JohnT]

Can ozone destroy CYA? I added enough for 20 ppm over a week ago (slow to dissolve of course) but analysis indicates none present now.

Ozone doesn't destroy CYA. 20ppm CYA is almost below measurable.

If you are going with bromine, why add CYA? CYA only stabilizes chlorine, not bromine.

 

[Curmudgeon]

The CYA was added before I was aware I had an ozonator. Just curious where the CYA went.

My question is, should I consider going to bromine, knowing that there is an ozonator, or should I cut the ozonator power cord and continue with chlorine?

And an implied question is, am I making a mistake adding insulation?

Curmudgeon

350 gal Infinity using BBB

 

[chem geek]

There is a known slow oxidation of CYA by chlorine and this may be accelerated at higher spa temperatures (it's also accelerated at higher pH). However, this is something that could have a measurable effect over months, not one week. As Jason says, I suspect this is just partially a test error. You could certainly add enough Dichlor for 10 or even 20 ppm CYA equivalent and that should get you more solidly into the 20-30 ppm range for CYA -- even if it got you to 40 ppm CYA that's not a big deal.

As for the ozonator and chlorine vs. bromine, that's up to you. If you find that chlorine loss is high, then you can see what happens if you disconnect your ozonator. If that helps, then great. If your chlorine loss is more normal -- around 25% per day with no tub use (but the water fairly hot) -- then the ozonator isn't hurting.

 

[learthur]

The answer is it depends....

In my pool my ozonator slowly oxidizes CYA over a time period of several weeks. I add CYA via trichlor tablets until I get my SWG I stalled.

So people use a bromine/ozone system. I chose not to as theoretically this combination can produce a carcinogenic compound.

But if you plan to drain/fill you spa frequently then it may not be an issue.