We purchased a new spa (Viking Legacy 2) that was delivered in September. We're using low levels of chlorine with the Nature 2 cartridge. Our initial water sample from the spa store showed that our alkalinity and ph were both perfect, so no additional chemicals in the beginning. We've been shocking with MPS. A couple of weeks in, the alkalinity and ph and started reading low so I balanced everything. Shortly after this, some foam started to appear, which gradually grew to be a LOT of foam. I reached out to the spa store, and they told me that it was likely detergent from our suits.
A couple of weeks ago, I cleaned our washer twice, then washed all of our swimsuits several times in the clean washer using no detergent. A week or so later, I did a full water change. As was the case in the store, the alkalinity and ph were perfect, so I chlorinated and we were good to go. For a week or so, there was no foam at all in the new water, and the only thing we introduced to the tub was 3 tbsp of MPS after each use.
10 days after the water change, I tested the tub and both the alkalinity and ph were low, so I first raised the alkalinity, then the ph, and then I added stain and scale remover (the chlorine levels were fine at this point so I left that alone).
From that point on, the foam came back. I'm not sure what's going on here, since we've eliminated detergent as a factor. I did get test strips to test the water hardness, and it came back at what I believe is an ideal level (at or a little below 120 ppm). The alkalinity has been stable since I added alkalinity increaser the first time, but the ph drops below 6.8 weekly. I'm using Spa Pure brand chemicals for all these adjustments.
Does anyone have idea what could be happening? If the ph is perfect in our hose water, so why is it shifting lower over time? And could whatever is causing that also be causing the foam? The foam is very annoying so it's something I'd like to try and mitigate if possible. My wife and I have also noticed that we may be reacting to the MPS, so I may start shocking with dichlor, if that matters.
