Why do I suddenly need frequent water changes?

[Susanj]

We’ve been having problems with the hot tub in our vacation rental lately . It's almost 4 yrs old and this has never happened previously. The last 3 refills were only 2, 3 and 4 weeks apart .

I don’t service it- we have someone else. I’m wondering what could be causing this. She says it needs changing because it’s stinky , foamy , cloudy , greenish and yet this is our off-season when we don’t have that many people in it.

Using the bather load equation,  we should be able to go about 1 month in summer and 2 months this time of year.

[ratchett]

Does the spa have an ozonator in it?  The ozonator could have failed and thus the original care routine is no longer sufficient to sanitize the spa? 

Without knowing more details it's hard to say (full disclaimer I'm also a newbie still trying to learn, "soaking" up as much info as possible from the forums)

[Susanj]

Hmmm, maybe. We replaced the original ozonator 8 months ago.

[Roger]

What are you using for sanitizer? And how are you using said sanitizer?

[Susanj]

It's a bromine spa so she uses MPS to get the bromine to 3-5 ppm. I go about twice a month and sometimes I use Dichlor. It worked for us before. 

[CanadianSpaTech]

Build up of bio matter inside the plumbing lines. I would start by running a plumbing line cleaner/disinfectant and then draining and thoroughly cleaning all surfaces. Clean your filters bi-weekly at most weather you are using the spa or not. Also use spa shock bi weekly as well. If you have a cloudy spa that is all the organic particulate (stuff you bring with you each time you use it...body oil, shampoo...) suspending in the spa. You would need to clean the filters then "Shock" the spa and run it until it clears and the clean the filters again once it has cleared. The spa shock brings the particulate together so they are big enough for the filters to pick up.