Hot Tub Question

[DaveD]

I seem to remember there used a portion of this site for hot tubs though I can't find it anymore. My Dad just put in a hot tub and was asking similar questions. I've seen tubs foam with Bromine and I personally have never liked it's odor. My suggestion to him was going to be chlorine. Since the tub is usually covered and indoors, I thought the chlorine level could be run lower since it shouldn't vary as much as an outdoor pool. Thought 1-3PPM more than adequate.

Am I all wet? Does chlorine off gas too much with the temps? Out side of keeping the water slightly descaling or neutral on one of the scaling indices and pH in 7.6-7.8 range, what else would you need?

[waterbear]

To the best of my understanding the chlorine level still needs to be higher than that because of the elevated temperatures of the hot tub. You want to make sure that you do not use any form of stabilized chlorine (dichlor) in an indoor tub. Bleach is going to be your best chlorine source. 4-6 ppm should be fine. TA will be constantly decreasing because of the airation and pH will be rising. Start with the TA high....maybe about 180 ppm for an acrylic spa and keep the calcium in the neighborhood of around 100 ppm and there should not be any major scaling problems. Be sure to shock after each use and to drain and refill the tub about every 1-3 months depending on usage. The smaller water vs. bather load really makes this necessary.

[DaveD]

If you were running bromine - what level would you run? Keep pH in what range, 7.5-7.8? If there is an ozone generator, can you run lower levels of either bromine or chlorine since the ozone will do a majority of the work and the bromine or chlorine demand would be significantly lower - decreasing the chance of a major swing in bacteria levels or need for higher ppm levels?

[waterbear]

If you were running bromine - what level would you run? Keep pH in what range, 7.5-7.8? If there is an ozone generator, can you run lower levels of either bromine or chlorine since the ozone will do a majority of the work and the bromine or chlorine demand would be significantly lower - decreasing the chance of a major swing in bacteria levels or need for higher ppm levels?

Bromine is less pH dependant and will work fine in pH as high as 8.0 but I would still keep it in the 7.4-7.8 range for comfort of the bathers.
Ozone will work with bromine and against chlorine. Ozone will convert the bromide ions in the water from your bromine reserve (you need to add sodium bromide on each refill when using bromine, even with the tabs in a floater!) into hypobromous acid. it will keep your bromine levels more constant and you might need to shock less. Ozone will lower chlorine levels and chlorine destroys ozone so the two tend to work against each other. Even with ozone I would run my bromine about 6-8 ppm or my chlorine about 4-6 ppm so there is enough residual sanitizer in the water to keep it sanitized while being used...remember the ozone will only kill bacteria that come in contact with it and there is no residual in the water you are soaking in!