Bromine Levels with Ozonator


New member
Sep 28, 2019
El Dorado Hills, CA
I recently purchased a house that came along with an above ground spa, which includes an ozonator. I've never owned a spa before, so I did a bunch of research on TFP, did a thorough decon with ahh-some, balanced the water according to the forum stickies that are always referenced, and then finally added my bromide and did an initial shock with MPS.

From everything I've read on the forum, it sounds like ozone does oxidize bromide into bromine, but a floater (or regular oxidizer addition) is still necessary. The problem I'm having is that the bromine levels always seem to be fairly high, even with little to no floater usage. When I did the initial MPS shock, I followed the directions on the bottle and ended up with about 19ppm of bromine. I had to leave the cover off and the floater out for like two days to get the level down to 5ppm.

Since then I've added my floater (pentair rainbow lifeguard) back in with the opening almost entirely closed off, and the bromine levels went back up to about 8ppm. So I'm not sure what I need to change in order to keep the bromine levels in the 2-4ppm range. Just leave the floater out entirely? Use the spa more? I already have the filter cycles dialed down to 60min per day, in addition to whatever runtime happens during periodic automatic heating.



Mod Squad
LifeTime Supporter
Jul 10, 2012
Tallahassee, FL
Here at TFP we use chlorine in both our pools and spas. Here is a link to a write up about it:

I hope this helps!



Bronze Supporter
Oct 20, 2017
South-Central WI
Welcome! Sorry nobody offered bromine specific help. A lot of people here (myself included) use chlorine in their spas. Not many use bromine. That said, there's nothing wrong with using bromine for a spa. I just chose to use chlorine because it seemed easier.

There is a sticky with some info on bromine, as well as a lot of discussion in that thread. If you haven't already checked it out, I would recommend reading it:

So I'm not an expert, but as I understand, bromine sanitation works as follows: Hypobromous acid (HOBr) is your primary sanitizer. After it oxidizes waste, the bromine becomes nothing more than an bromide ion, Br-, and no longer does anything. This can be reactivated back into HOBr to be "reused" by the addition of an oxidizer. This oxidizer can take the form of chlorine (such as unscented bleach or dichlor), MPS, or ozone. It doesn't really matter which one. All that matters is that you've added enough of a bromide bank (total number of Br- ions) at the start that you can reactive enough to maintain the proper level of sanitizer. As outlined in the above sticky you need to add sodium bromide until you have added 30 ppm of sodium bromide in total. After that you add enough of your choosen oxidizer (chlorine/MPS/ozone) to maintain the appropriate level of bromine sanitizer.

So I'm not sure what I need to change in order to keep the bromine levels in the 2-4ppm range. Just leave the floater out entirely?
You said your spa has ozone. If the ozone maintains the bromine levels at a suitable value (the sticky says to shoot for 4-6 ppm), then remove the floater. You would use a floater to maintain the level at 4-6 ppm if you didn't have an ozone generator. Don't throw the floater away though, it would be a useful backup if your ozone generator died.

Are you using a bromine specific test kit? Chlorine ones will work, but they are off by a factor of 2.2 if I recall correctly, and I can't remember which way they are off. Around here we teach that a quality test kit is important to maintaining properly balanced, sanitary water. We do not like test strips as they are generally quite inaccurate which makes maintaining good water quality difficult or impossible. FAS-DPD test kits are usually recommended around here. The Taylor K-2106 is a test kit for bromine with the FAS-DPD test. I also highly recommend the Taylor Speedstir, as it makes performing all of the tests very easy.


Well-known member
Sep 9, 2016
denver, CO
I'm a bromine user and a big fan for 30 years. What you have noticed empirically I have established experimentally -- bromine with ozone is a beautiful thing! Here's a few thoughts of mine on the subject

1. this is a personal preference thing of course, but over the years I have developed a dislike for the bromine floaters, mainly because I don't see the point. I maintain my bromine spa just like a chlorine spa -- "dichlor then switch to bleach" and the whole 9 yards. If floaters were so great for bromine why aren't then seen en masse in chlorine spas? Folks seem happy enough with dichlor and bleach for a chlorine spa (and i switched over to chlorine just to experience the certain happiness), so i just don't get the assumption that bromine is difficult, more complex, a pain in the butt, etc --- one person (as I was coaching through an ahh-some purge) even commented to me that his dealer held that his bio-film contamination problem was because he was using bromine.

2. the beauty of bromine when there is a good strong corona-discharge ozone generator on board (check yours) is that the vacation planing is easier! I am not making this up --I have personally found that my ozone generator is capable of maintaining a (barely) measurable level of bromine all by itself -- with no bather load of course. What happens in a bromine spa with ozone is that the sanitizer never really gets to zero -- it just gets real close. Of course you have to have a clean spa to do this, and not many really do -- nor are they willing to test this to see -- but its absolutely true: If bromine decay goes to zero with (strong enough) ozone on board, you have biofilms. -- or an leaky cover, or dust gets in , or a stray spider gets in, etc.

3. Another side effect of ozone on board is that you have to be very careful with shock -- its VERY easy to achieve SLAM conditions and then (if you spa is clean) you can be in for a long wait before its safe to get in! this is true of course for "alternative" oxidizers like MPS as well which makes bromine. I have turned instead (see #5) to a product that saves me from this as well.

4. I have concluded that the reason bromine is perceived to be difficult/etc. is because the stores want to sell you something. and then they want to sell you more things to make the first thing work better (i'm being hyperbolic here of course...). What is so difficult about spending 45 seconds to dump in sodium bromide salts at startup? this has escaped me for years --- put the salts in, forget the floater, and treat it just like a chlorine spa.

5. the other really interesting thing I've learned over the past 2 years especially is regarding a product by the makers of ahh-some -- called "hot tub serum". I"m usually quite allergic to superfluous products (see #4 above) but I have to say this stuff has made my life easier. I even have sanitizer decay rate data proving that this stuff improves the chlorine or bromine decay rate and will allow you a mistake here and there (let CL go to zero) with no consequences. Its true. I"m one of those anal guys that enjoys impeccable water maintenance but it turns out I'm not perfect 100% of the time and (gasp) the CL level might go to zero -- or the bromine can go to zero if the ozone isn't there ( I turned mine off to experiment). if you are 1% less than perfect this saves the day. it does a "mini purge" and effectively SLAMS your tub while allowing you to use it. I also experimented and deliberately let my spa water go bad, and then resurrected it with the Serum -- What would normally require a SLAM and three days before the spa was usable -- now takes me 24 hours.

6. 2nd the Taylor K-2106. boom

So far, the only downside of bromine I have found is that during the ahh-some purge you can't add hydrogen peroxide to neutralize the chlorine before dumping on your lawn. I purge with lots of bleach (ahh-some releases bad guys that traditional decon won't, so they need to killed). I don't really measure the sanitizer level that I actually acheive (not worth the effort) so I'd say 50ppm equivalent FC is not uncommon for me. not something i want my lawn to experience, even for the short time before the ground neutralizes it. So I dug a french drain. problem solved
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