Chlorine Tablet Floater

[graysilm]

I have now owned a hot tub for about 3 weeks. I feel like I have gotten the hang of maintaining water chemistry. The only times I have a difficult time maintaining the water is when there are heavy bathing loads. On a few occasions on the weekends there have been times when there are people constantly in and out of the tub for 18+ hours straight. I am wondering if it would be appropriate to use a tablet floater during these occasional times of heavy long duration use. The manufacturer of the tub advises against using floaters but I feel like it my be the only option to maintain sanitary water during heavy use. My tub holds around 300 gallons of water. Thoughts?

[chem geek]

You can either carefully add bleach in between when people are in the spa or as you point out you could use a Trichlor floater. You need to be careful though. Trichlor dissolves more quickly in hot water so you'd have to use a floater that could be dialed way down -- not a pool style one but a hot tub one where the top is sealed (you add tabs from the bottom). The main risk is that too much Trichlor is added too quickly. Also, it will lower the pH and TA over time so unlike when using bleach you'd want the TA to be higher -- at least 80 ppm (for pools it's usually 100-120 ppm when using Trichlor). For every 10 ppm FC added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm and decreases Total Alkalinity (TA) by 7 ppm. If you had 80 ppm TA, then the pH would drop from 7.5 to 7.1 if there were no carbon dioxide outgassing (there is, so it won't drop by that much).

When you add chlorine it will oxidize bather waste and that can smell. So it will be more like a commercial spa, but that's the way it is if you have such continual heavier bather load.

[Dizzy McMuffin]

Is it possible to use chlorine in powdered form in a floater. I find that sometimes using tablets they break up into small chunks and I'm a bit worried about them getting into the pump system.

[Loopcity]

You can just add a tsp or 2 of dichlor and small dose of MPS during the day of heavy usage. In my experience, the MPS oxidizes the chloramines that cause irritation and smell before they can do that. Chem Geek is certainly more qualified to answer this.

[Dan The Spa Man]

Late to the thread but one should never use tabletized chlorine in a floater in a spa. The spa is typically covered when not in use and tablets will emit chlorine gas. Not only is it unhealthy and potentially dangerous, but it can wear out your cover, headrests, jets, etc. prematurely. DiChlor (If you're using chlorine) would be the safer bet as it dissolves rather quickly and emits the least amount of gas. Or as others have pointed out- MPS and a mineral stick (Spa Frog, Nature II, etc) may be the play. Good luck going forward.