Spa Chemistry vs. Pool Chemistry

[Alan2144]

Hi Folks!

Please forgive any missteps in this, my first post.

I have been reading with interest the many posts on the respective chemistries of chlorine and bromine, converting from one to another, etc. I have yet to come across any information specific to my circumstance, so I thought I would simply ask it here. So sorry if I missed the appropriate thread!

I have an outdoor, in-ground pool (~30,000 gallons) sanitized with chlorine. If I were to pick up a stand-alone spa (~500 gallons), install it separate from but relatively close to the pool, and sanitize it with bromine, will I have to be concerned with the brominated water mixing with the chlorinated water as the little savages run back and forth between the pool and the spa? Would that be enough inter-mixing of chlorine and bromine to be a problem? If so, I imagine I could install an outside shower of some sort, but still... I couldn't guarantee that the waters would not be mixed by the bathers.

Should I consider chlorinating both, or brominating both, with all the really interesting chemical caveats I have been reading about here?

Thanks in advance!

Alan

 

[chem geek]

Welcome to TFP!

The amount of water going from the spa to the much larger pool will be negligible so you do not need to worry about your pool becoming a bromine pool. If your spa had 100 ppm bromide in it from accumulated bromine usage, then even transferring one gallon of water from the spa to the pool (and that's likely way more than gets transferred) would result in adding 100*(1/30000) = 0.0033 ppm bromide which is of course negligible. Even 100 times this amount is still only 0.3 ppm.

As for how to manage the spa, that's up to you. If you use the spa every day or two then chlorine works well with the Dichlor-then-bleach method described in this sticky. Just as with the pool, you'll need to add chlorine frequently, every day or two. This is especially true if you have an ozonator in the spa since that consumes chlorine in between soaks, though lowers chlorine usage from bather load. If you only use your spa on weekends and especially if you have an ozonator, then bromine is easier since ozone can make bromine from a bromide bank.

 

[JasonLion]

I would use chlorine for both, but you don't have to. You can mix and match as you wish. Chlorine doesn't bother bromine at all. And the quantities of bromine that will get into the pool will be small enough so they don't matter.

 

[pooldv]

My pool is saltwater and my hot tub is bleach. It is handy to have bleach around to use in my pool when the SWG needs an assist.

 

[Alan2144]

Thanks to all for the prompt and friendly and expert info! I can see that TFP is the place to be...

Alan

 

[JVTrain]

I have a similar setup. Pool, isolated spa. I tried a brominated tub initially, but didn't enjoy the smell of bromine in general and find my chlorine tub (dichlor then bleach method) to be great and I don't have to worry about bromine bank, tablets, etc. It's easy enough to try both and if you don't like your chlorine tub you can convert it to bromine w/o draining water. You can go from bromine to chlorine tub, but need to drain the water first.

My tub was bromine last year at this time and there was LOTS of my kids back and forth between the frigid pool and warm hot tub. No issues to be concerned about.