Flagstone

Hi all, We have a 500 gal spa (using bromine as a sanitizer) and whenever we run the jets, the pH goes way up. I've been told that this is a result of the aeration driving out the carbonate in the water. I presume this carbonate comes from the baking soda we add to keep the alkalinity in range (we usually keep it at about 80 to 100). Is there a better choice, such as a phosphate, for raising alkalinity or is there another way to keep the pH from going up so much when we run the jets? Thanks!

Thanks Waterbear. It took a little over 1-3/4 cups bleach, but the bromine eventually climbed to >10 ppm. As a side note, I let the spa run out in the sun with the cover off for a while this morning and within an hour or two it was back down to 6 ppm and the pH also returned to it's previous level, about 7.5. The startup packet I recieved contained 2 oz sodium bromide. I had a very hard time getting the oxider to bring the bromine levels up so I added a second 2 oz. packet and eventually, 1/2 of a third. This seemed like a lot to me, but it fits with your 1/2 oz per 100 gallon guideline.

Is there a way to tell if there is enough sodium bromide in the water? My first thought, based on your comment above, was to check for chlorine following a shock as it should all be consumed by the bromine. If I add the correct amount of chlorine (bleach) and it is not completely consumed oxizing the bromine, then there must not be enough bromine, right? But according to my test kit, chlorine and bromine must exist as a fixed ratio of about 2.2. What am I missing? As a side note, I did my first bleach shock tonight with 1-1/2 cup clorox in a 500 gal spa. The bromine didn't jump up quite as high or as quickly as I expected and that made me wonder if I had enough sodium bromide in the water. Also, the alk stayed fairly low, but the pH jumped way up. Thanks again.

Ok Waterbear, thank you very much for your help!

Thanks for the help, Waterbear! Just a couple more questions: 1) So the main thing to watch before getting back in after a shock treatment is the bromine level? That is, we can get in soon after doing a small shock with bleach or MPS as long as the bromine level doesn't go above 8 to 10 ppm, right? 2) When shocking with MPS (potassium peroxymonosulfate) do I still need to drive the bromine to >10 ppm or does the MPS provide enough additional shock/sanitizing on its own that the bromine can stay lower? I guess it's a question of whether the MPS is immediately consumed by the bromine conversion or whether some stays in the water as a sanitizing agent. I added 4 ounces (the instructions recommend 2 to 4 oz.) last night after we got out and the bromine went from 2 to 8 ppm. Again, thanks for you help. I've been to at least four local pool/spa stores and so far all of them have been wrong on at least one (but usually more) aspect of using bromine. It's a wonder anyone around here can maintain a healthy spa.

We have a new 500 gallon above-ground spa, and after lurking here for awhile I think I'm starting to get a handle on the chemistry. I'm still a little confused, however, about weekly shocking. We started the spa on bromine with a kit by "Brilliance." It consisted of some pH/alk adjustment chemicals, a pouch of metals reducing chemicals, bromine, and an oxidizer to activate the bromine. For the first couple days I had a little trouble keeping the bromine above zero for very long, but now it seems to be doing well. I'm using brominating tablets (1-bromo-3-chloro-5, 5-gobbledygook)in a floater and add 1 to 2 ounces of 6% bleach after every use. The spa also has an ozone generator that runs with the continuous filter cycle. The vitals: br=3 alk=80+ pH=7.5 ch=250- The water is clear, but has a very slight blue-green tint and a touch of a musty odor. I'm about a week into it, so I figure it's time for a weekly shock. But with what? The local spa store recommended potassium peroxymonosulfate because I shouldn't use chlorine products with bromine (yes, I know this is not true ) and because we would only have to wait a few minutes before getting back in the spa. I'm leary that either the product is not strong enough to do the job or maybe we shouldn't get back in so soon. So... 1) Should I use this product? 2) or should I just use bleach (but more of it)? 3) how high should I expect my bromine level to go when I shock correctly? 4) after adding bleach (a small amount just to keep the bromine up) how long do we need to wait before getting in? Thanks for your help!