How do I know if that little black box with a clear tube running from it is doing anything? I don't have any problems with chemicals, I do a weekly treatment that works fine.

How old is your ozonator, and can you smell any ozone in the tub?

It was new equipment in 1999. Not sure what ozone smells like.

If you're able, you can perform an amp draw with a electric meter amp clamp to see if it is drawing amps.

It's hard to describe the smell of ozone, but it's definitive when initially opening the cover on a spa that is constantly injecting it.

Would I see bubbles or anything when the pump is off?

Ozonator doesn't generate the bubbles.

The circulation system does.

However if the bubbles have O3 in them, then you'll definitely smell it. Smells like pretty intense lightning. Seeing as that thing is 8 years old I'll give your ozone generator about a 5 percent chance of being in the 'still working' category.

My ozonator is a 1998 model & it still works great, you can smell it & see the bubbles being injected into the water. At night you can see the light coming from inside the ozonator as well.