Hi everyone, first off I have found this forum to be the most helpful resource for my new-ish Freshwater hot tub on the internet. I was hoping to generate a discussion on many of the various topics scattered across this forum in a single thread.
So, here are some of the mysteries I think I have solved, and some mysteries I still have. Hopefully this thread can generate some feedback, debate, agreement, and some new mysteries. Thank you all for reading!
Tub in question - 2021 Flash w/ Freshwater, 350 gal, high bather load (at least 1 ppl per day, often 1 or 2 ppl a day, sometimes 1 or 2 ppl 2x a day). Salt system at 7. Salt added at fill is 1/2 of recommended amount. Hardness ~35PPM
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Part 1: mysteries I think I have solved:1. Lack of FCL on freshwater systems - Based on my trial and error, I have found that the single most important factor in getting your salt system to actively generate and register FCL is calcium hardness (the second is CYA lock see #3). I live in drought stricken SoCal so our water is basically dredged from the bottom of a mostly empty reservoir and hella hard (400 - 500PPM). After a few drain's and refills using the vanishing act (regular size) I struggled with getting the system to produce FCL. I purchased the XL vanishing act, and this finally got my water hardness down to 25 - 50 PPM and the tub finally started showing FCL on strips (for a bit, again see item #3). After I used the XL I put it back in the bag in the hopes that I could possibly either get one more fill OR minimally use it to bring down hardness between fills if it drifts up.
2. Salt levels on fill - The dealer, multiple sources on the web, and this forum all have agreed that you should limit the amount of salt you put in on first fill to 50% of the recommended amount. It seems that sweat and other chemicals drift up salt over time.
3. Dichlor (granule) vs. Sodium Hypochlorite (liquid) and CYA lock - Based on bather load I shock 1x a week and sometimes 2x a week and was using the Dichlor provided with the tub (and on local dealer's advice to avoid liquid chlorine). After a bunch of googling, I finally found an internal DEALER FAQ document from Hot Springs (link below). The Freshwater system generates Sodium Hypochlorite (same as bleach). Also, the document clearly states that dichlor chlorine adds Cyanuric Acid and will lead to the dreaded CYA lock which stops the effectiveness of chlorine. After refilling at six months, and now likely again after only 4 months, my conclusion is
You should ONLY use liquid chlorine in your freshwater tub!! That said, it seems I will need to be more on top of PH levels with Sodium Hypochlorite vs. Dichlor, but that is a trade off I think makes sense.
3.a Link to internal Dealer FAQs that provides detailed information on Salt System chlorine generation
https://spaworld.zendesk.com/hc/en-us/articles/360000971076-Hot-Spring-Spas-Freshwater-Salt-System-FAQ3.b Link to website on CYA lock and why you shouldn't use dichlor granules in a hot tub.
https://www.aquamagazine.com/retail/article/15122093/cya-ally-for-pools-havoc-for-hot-tubs#:~:text=CYA%20Buildup%20is%20Real&text=This%20means%20for%20each%2010,CYA%20in%20only%20seven%20weeks.Part 2: Mysteries I have not yet solved4. Why does my tub's salt system show a 'high' level but test strip shows salt levels at 1750PPM or below? I think this might have something to do with CYA lock? I do know that the salt meter on the tub was in the 'low' range, and in the period of a few weeks it shot up to 'high'. The yellow light on the logo of the tub is a constant source of anxiety and mocks me every time I look at it. This is a mystery.
5. Should I be using more / different / chemicals or sanitizers? I am using Sodium Bisulfate for PH / Alk down, Sodium Bicarbonate (Arm and Hammer) for PH / Alk up, and liquid chlorine for shock / top off on heavy bather load days. I have been randomly throwing MPS in the tub, although I am suspicious that it could be raising salinity, creating some other problem (CYA lock?) Also, should I consider a Silver Ion Sanitizer? Could I add a Frog At Ease system to Freshwater? This is a mystery.
6. Phosphates what is high, low, OK? And should I do anything? A recent phosphate check shows about 30PPM phosphate. I think that is OK? I can't find a good answer what a target is. Also, should I consider using Ahh-some bio cleaner when I refill next (I took delivery of the tub a year ago and never did any bio treatment)? This is a mystery.
7. An 'on the go' water softener instead of vanishing act? As noted above, I finally got my calcium hardness down using the XL vanishing act. The XL vanishing act is like $60 bucks. Doing the math, if I need one every time I refill the tub (hopefully as I solve the mysteries the refill only happens once a year). A 'on the go' softener costs about $200 and can be recharged with table salt, and the resin needs to be replaced (about $90) every 7 to 10 years. The math seems pretty straightforward that getting a portable softener makes sense (and probably more environmentally friendly.) What am I missing? This is a mystery.
