I have a custom built in-ground 1200 gallon bromine spa, which really looks more like a small plunge pool (photo below). It is freeform shape approximately 7 ft x 10 ft and 3.5 ft deep and has a Pebbletec plaster finish and a waterfall. Equipment specs are as follows:

8 returns (7 jets/1 waterfall), 1 skimmer, dual main drains
1.5 Hp Pentair WhisperFlo Pump
1.5 Hp Air Silencer Blower
Jandy 460 sq ft Cartridge Filter
Laars LX250 Gas-fired Pool and Spa Heater

I follow the 3-step bromine process (bromide salt reserve, Clorox oxidiser, 1" bromine tabs in floater) and am a huge fan of the BBB process.

The general recommendation for spas seems to be to drain and refill every 3 months, but I suspect that is really referring to traditional under 500 gallon fiberglass spas, not an in-ground spa that is more like a pool. My question, therefore, is how often should I completely drain and refill a spa-ool such as mine?

Thanks so much.
Sandi in Dallas

1st of all...thats awesome. 2nd....I have no idea but would suspect it depends on the use and heating cycles. If you are using it for cool dip water than it requires less chlorine yada yada yada...but spas really seems to be a bacteria breeding ground

What do you keep your chlorine at BTW

I can't use chlorine because of the heater, so I have bromine instead. I have a sodium bromide reserve, use a floater with 1 inch bromine tablets, and dose with about 1/2 cup of Clorox every other day to oxidize the bromide into bromine. This gives me a (theoretical) chlorine reading from my test kit of around 2.5 which equals a bromine reading of 4.4. This seems to work pretty well as my water is always clear and sparkling. We don't heat it except during the Texas "winter" (December - March) and even then, I use the term "winter" somewhat loosely!

Oh I hear ya I am in Oklahoma.

The bromine levels and the water circulating regularly seem fine. I am thinking you should have have to drain every 3 months. I would just keep it clean and use it all the time. I wish my pool could be hot tub at times but with the weather we both have its getting close.

What color pebbletec is that?

The PebbleTec color is SANDY BEACH. I wanted a very "natural" water color because of the real rock edging and greenery surrounding the spa. I wanted a "grotto" kind of feeling in my very small yard. When the sun is out and the sky is blue, the water color is very much like the soft blue/green you would see in a shallow forest stream and I am really pleased with how it came out. When the sun isn't out and the sky is grey, the water is a soft grey green, a bit like the color of the ocean.

Here's a couple of slightly better pics that show the water color. The PebbleTec is actually a pale beige color (out of the water).

There's no problem for you using bromine, but it is not true that you cannot use chlorine because of a heater. Millions of pools and spas have gas heaters (most with copper heat exchangers) and use chlorine with no problems nor damage to the heaters.

Thanks, all, for your most helpful comments.

My original question still remains ...... is it necessary for me to completely drain and refill on a regular basis, considering the size of the spa-ool and equipment that I have? And if it is necessary, how often should I drain and refill?

Thanks
Sandi in Dallas

I can't be as definitive about bromine spas, but for chlorine spas when using Dichlor-only the general Water Replacement Interval (WRI) rule seems to work which is

Days Between Water Changes = (1/3) x (Size of Spa in U.S. Gallons) / (Number of Bathers)

where soak time is presumed to be around 20 minutes. So in person-hours this would be

Days Between Water Changes = (1/9) x (Size of Spa in U.S. Gallons) / (Number of Person-Hours)

When using the Dichlor-then-bleach method, one can go around twice as long as this formula indicates. I'm guessing that bromine might be roughly the same as the Dichlor-then-bleach method, so would be the following

Days Between Water Changes = (2/9) x (Size of Spa in U.S. Gallons) / (Number of Person-Hours)

So for your spa this would be

Days Between Water Changes = (2/9) x (1200) / (Number of Person-Hours)

so even with 1 person-hour of soaking every day (so 2 people for 30 minutes every day, for example) that would be changing the water after roughly 9 months. I don't see any need for you to change the water every 3 months. Probably once a year would work fine -- even less frequently than that if you don't use the spa as much.

Thank you very much, Chem Geek, for going to all that trouble to lay out the correct calculations for me. It is most appreciated, and kind of what I had in my mind also. I'm at the one year mark, we don't use the spa every day - mostly weekends - so I'm going to wait to drain and refill until the weather here in Dallas isn't 106 degrees (which will probably be in September)!