Do I really need to change the water every 3-6mos?

[swimspaguyy11]

I have a 2000 gallon swim spa that has had the same water in it since end of last summer. I know the recommended water change is 3-6months but typically any recommendation for that says the water will get too far out of balance and nasty and require it. The thing is, my spa is crystal clear, the water is perfectly balanced, I do not have to put any chemicals in it other than a bromine tab or two every couple of weeks and shock it with 2oz of mps every couple of weeks. Ph doesnt budge. I rarely use it this time of year and when I do use it, its typically just me and sometimes my wife and we are usually very clean when we use it (usually just nights in the winter) I also only run it at 98F so I don't do a ton of sweating in it and I only use it as a big hot tub and don't exercise in it. I never have a single guest use it, so I know its never been peed in.

So with all that being said, is it still a good idea to drain it and change the water? Thanks

 

[Mdragger88]

In general the cues for needing a purge, drain, & refill are “persistent” cc’s in a chlorine tub & higher standby sanitizer demand in lieu of obviously funky water.
Since you can’t test for anything but total bromine you will need to rely on your assessment of sanitizer demand as well as the look of the water along with checking the calendar.
Your spa is large which is helpful bather load wise. Basically a small, hot pool that is susceptible to biofilms. You should probably do a purge, drain, refill once a year at least. One person in your spa is equal to having 13 people in my 26k gallon pool. So…. kinda like a party everytime you use it. You still sweat & shed skin cells/bacteria etc. even if no one pees in it & it does eventually build up.