I have a "Hot Springs" hot tub that takes chlorine for shock and MPS Oxidizer for additional water purification. If you deal with Hot Springs, you know their prices are very high and I've found much better sources for chlorine and now I'm looking for a (lower priced) source for the MPS.

Can I get this stuff at a normal pool store or is it a Hot Springs-only type of product?

Thanks!

Chances are you can find it at most pool supply outlets as "non-chlorine shock". MPS=monopersulfate.

My favorite source is The Spa Depot - if you google it, you can go to their site and order online as "Oxy-Spa Non-Chlorine Shock". They offer discounts for purchasing 6 lbs vs. 4 or 2 lbs. When I researched prices for spa chemicals several years ago, this place beat everyone else's, so I've stuck with them ever since.

I also have a Hot Springs spa - the Vista to be exact and am using the BBB method for the first time in it. Talk about finally having clear, sparkling water!

Best to you,
Jan

Thanks Jan.

Can elaborate on the BBB method for your spa? I've just been using chlorine and MPS and I haven't had any problems with water quality, but if there's a better, cheaper way, I'm all ears. I'm under the impression that if you have a chlorine spa you can't just switch over to bromine. Is that not true?

Thanks!

You can read Using Chlorine in a Spa for more info on the Dichlor-then-bleach method. This is the least expensive, safe and sanitary way to manage a spa and is essentially like BBB with pools. The Dichlor initially for around a week is to build up the CYA level to around 30 ppm. The bleach after that maintains the Free Chlorine (FC) level while not increasing CYA. In most spas, you need to use Dichlor about one day a month since the CYA will drop around 5 ppm per month. Though one can try and use pure CYA to raise it initially, the Dichlor isn't expensive in small quantities and dissolves quickly. Note that for pH stability one needs to have a very low TA level, as low as 50 ppm if needed, and that the use of 50 ppm Borates also helps for pH stability when the TA is low.

Note that some people target 1-2 ppm FC before their soak and add chlorine after their soak in order to minimize chlorine (and chloramine) smell. Though this usually gets to zero chlorine and no sanitation during part of the soak, bacteria take 15-60 minutes to double in population so you don't get any uncontrolled bacterial growth nor biofilm formation and the chlorine "shock" after the soak kill off whatever was shed. The risk is in person-to-person transmission so if that is a concern then target a higher FC level (usually around 4 ppm) so that there is still some measurable FC after the soak. So while this shouldn't be done in a commercial/public pool or spa nor when you have people over sharing your spa (especially if any have diarrhea, even if they don't know it yet), it is probably what most people do and we haven't had any reports of any problems.

Switching from chlorine to bromine is very easy and does not require changing the water. One simply adds sodium bromide to provide a bromide bank and any oxidizer (chlorine or MPS) added will convert it to bromine.

It's converting from bromine to chlorine that is more difficult and requires a complete water change to remove any bromide in the water.

Hello Bart,

It's December 12, and I just discovered your reply to my post. I can't believe I didn't discover it sooner . . I like to answer all posts directed to me. At least Chem Geek chimed in with good info in the meantime, and I hope you've been enjoying your spa this season.

For years I have run my spa using dichlor (chlorine powder for spas), and this fall/winter I decided to maintain it the same way I maintained my pool: using regular household bleach. I started off using dichlor and when I had about a 20 ppm buildup of stabilizer I switched to bleach, and I just cannot believe how clear my spa water is, even after all these weeks. I never knew that dichlor was adding stabilizer to my spa and creating a chlorine lock, which was evident because my water was always hazy. Now I know why all the books say to change your water every 6 to 8 weeks. And that's it, in a nutshell - it works.

Best,
Jan

Perhaps unhelpful, but MPS is DuPont OXONE and CAROAT by Evonik (used to be Degussa). I am being similarly frustrated by the expense of MPS and its nonavailability in bulk (presumably less expensive).

In/by the summer, when I can spend more time outside than today @ 10°F, I'll seriously consider changing to H2O2 that costs $100/35% 5 gallon carboy. H2O2 can join my collection of other chemicals.

Hydrogen peroxide is incompatible with chlorine and in fact can be used as a chlorine neutralizer. If you use the Dichlor-then-bleach method, then you will not need any MPS nor hydrogen peroxide or any other oxidizer and won't need to shock regularly either. Or, alternatively, you can use a bromine method where you can use either Dichlor or bleach as your oxidizer to active more bromide to bromine while the bromine tabs in a floating feeder provide a consistent baseline bromine level.

Hydrogen peroxide is not an EPA-approved disinfectant for pools or spas. It is approved in Australia, but you have to use rather high levels for sanitation.