What is the Best Hot Tub for Sanitation

[Chas]

I used to sell HotSpring tubs, and I find that their little circ pump does the job. If you want to buy a tub with a larger circ pump, fine, but I sure wouldn't make my overall choice based on that item alone. Their pump is tiny, and that saves you money on electricity, but it really does the job quite well.

HotSpring tubs come with Ozone standard on the Highlife Series, and optional on the Limelight series. It is a good system: you add MPS after each and every use, shock with Dichlor once a month (or after a crowd) and you stay safe. Plus, you are soaking chlorine-free except for a day or so after the shock, again, that's once per month.

One caveat: the air bubbles which rise from the bottom of the tub are very important indicators: when they slow or stop, you must clean or swap the filter right away, or you may lose the ozone generator which only has a one year warranty. All the rest of the tub has 5 years (7 on the shell and structure).

[AaronSantaCruz]

I looked at the kill rates for chlorine vs. silver vs. copper. This is very alarming. I wonder how safe it is to actually use silver on a regular basis and only shock weekly with chlorine. I know there have been raging debates about adding chlorine or shock after each use. Choosing the hot tub seems now like the easy choice. Deciding how much and when to use MPS and chlorine is more of a challenge.

[chem geek]

It's not really alarming; it's just a difference in kill rates.  Copper ions alone would be more of a problem since they do not even inhibit fecal bacteria, but silver ions at least kill fecal bacteria and Pseudomonas bacteria faster than they can reproduce.  By themselves (i.e. without MPS) they are not approved by the EPA because they do not kill quickly enough to pass the strict criteria in EPA DIS/TSS-12.  That criteria is designed to have kill times fast enough to prevent most person-to-person transmission of disease since that is a risk in commercial/public pools and spas where one sick person can infect dozens of others.  There is far lower risk in a residential pool or spa.

You've heard in this thread how there are thousands of users using this method (i.e. ozone, silver ions, weekly chlorine shocking) without apparent incident.  I kept track of dozens of hot tub itch/rash/lung incidents (and one person who nearly died of Legionnaire's Disease) on another forum in this post.  The most common causes were inconsistent disinfection so periods of no chlorine or bromine, but using Dichlor for too long can also be a problem since the CYA buildup makes chlorine less effective.  Some alternative systems are iffy, hot temperature can be a problem for some, pressure from jets for others.

There weren't any incidents when people started using the Dichlor-then-bleach method, but there wasn't a large enough sample to be sure since by far most users used Dichlor-only followed by users of bromine.  According to national survey data of hot tub users, around 50% use chlorine (pretty much Dichlor), 33% use Bromine (often with tabs), and the rest a mix of metal ions, non-chlorine shock, and other methods.

[AaronSantaCruz]

I am impressed with the research you are doing. I wasn't sure what your opinion is on using ozonator and silver ions with a weekly chlorine shock. Is this the system that led to someone getting Legionaire's Disease?

[chem geek]

No, the person who nearly died from Legionnaire's Disease used a soft tub in a hotel where the hotel staff did not properly disinfect it and just changed the water between guests (this doesn't clean out the plumbing).  This post describes her experience though some links in that post are broken so you can read more about her situation here, here, here, and here.  By the way, when I asked if people reporting these problems on the forum contacted their dealer about such issues, most had not.  So I don't know if dealer statistics are necessarily the best way to know if a system is working.

I also communicated directly with the man who got hot tub lung which was also fairly serious (he ended up in the hospital).  That was from using only Aquafinesse and is described in this thread.

You have to keep in mind that the risk is a statistical one so there are lots and lots of people using all kinds of systems that absolutely swear by them and claim to never have problems with anyone using that system and they may very well be right.  That is not the same as using a system across hundreds of thousands or millions of spas or pools.  The CDC keeps track of such large scale statistics for recreational water illness in the hundreds of thousands of commercial/public pools and spas (and other recreational water such as lakes, streams, ocean beaches, etc.).  What becomes very apparent is that one cannot use incidents of "no problems" as meaning there will never or very infrequently be "no problem".  If one doesn't really understand the fundamentals of the chemistry and biology, then one is just going on statistical luck.

As for my opinion on using an ozonator and silver ions with a weekly chlorine shock, it's riskier than maintaining a residual disinfectant at all times or nearly all times.  As for the degree of risk, it likely depends on how much residual ozone gets into the spa seating area and for how long/frequently during each 24-hour period.  Silver ions alone may prevent uncontrolled bacterial growth, but they aren't like chlorine.  Ozone kills quickly, but ozonators are not usually designed to maintain an ozone residual in the tub because it has the potential to outgas and ozone is an EPA regulated pollutant and can be irritating or cause long-term damage to lungs (and isn't great for hot tub covers, pillows, etc.).  So a properly designed ozone system won't put much ozone in the bulk water, but if that is the case then it's nor providing bulk water disinfection and only killing pathogens that circulate through the ozonator.

So maybe a particular spa dealer's spas that they sell have ozonators that are powerful enough and kept on long enough to provide enough residual to make the spas safer and the silver ions fill in between times when the ozonator is on.  The problem is that there are no regulations specifying specific minimum amounts of ozone in residential spas nor are there inexpensive accurate ozone test kits (though there ARE test kits -- they are just approximate or they are expensive).  Ozonators can also fail but you may not know it if you aren't testing for ozone in some way.  So I can't really comment on the degree of safety of the system.  I can say that if you maintain a chlorine (or other EPA-approved disinfectant) residual at all times, you will have a safe spa.  One slight modification to this is to start off a soak with a low chlorine residual such as 1-2 ppm FC.  That may not last through the soak especially if the bather load is heavier, but most people find it more pleasant (less chlorine/monochloramine smell).  Monochloramine is formed from the ammonia in sweat and urine so provides slow disinfection (not much unlike silver ions), but technically one doesn't have the fast disinfection preventing person-to-person transmission of disease.  When you add chlorine (or MPS if silver ions are present) after a soak, you quickly kill off anything that may be left and prevent it from growing on spa surfaces.

If you don't want to use chlorine all the time, then with the silver ions you can use non-chlorine shock (MPS) and get fast disinfection.  That's more expensive than chlorine, but it's an EPA approved alternative (at least in Nature² product since technically the EPA registers products, not chemicals).  If you want to rely on the ozonator with silver ions, that's up to you but I consider it riskier because one doesn't know the strength of the ozonator and amount of residual ozone that is left and for how long.

[AaronSantaCruz]

Thank you for your thorough and thoughtful response  With your perspective and knowledge that you outlined, I should now be able to determine a relatively low risk approach once I purchase a spa. My thinking is to find a spa that has the most powerful self contained ozonator (no leakage of ozone) and a good recirculation rate. I have been wondering though if the Jacuzzi Clearray has any advantages to ozone but there seems to be no information or research available online whatsoever on this. That is definitely a concern about knowing whether the ozonator is actually working at any given time. Clearray has an indicator light when the bulb needs replacing but can you rely on this.

[chem geek]

The CLEARRAY® Water Purification System is a UV system so leaves absolutely positively NO residual in the water whatsoever.  It only disinfects water that passes through the system and it does not oxidize bather waste (it breaks down some larger molecules into smaller ones).  So based on what you want to do it makes no sense to use such a system when you are wanting to use an ozonator and have some ozone in the water.  Note that ozone is a strong oxidizer so having ozone in the water may have your hot tub covers, pillows, and other components not last as long as they would otherwise.

As for your ozonator, there are two types.  One uses a UV bulb to generate ozone so you can just see if the bulb is on in that case (though in some cases the bulb may be on but not producing strong UV).  The other type is corona discharge (CD) which is a more powerful ozonator.  Some ozonators have a light that tells you if it is on though that still may not indicate that all parts are functioning correctly.  Probably the easiest way to know if an ozonator is working is to have it on most of the time and note the 24-hour chlorine demand with no bather load.  With no ozonator, the FC will usually not drop more than 25% in 24-hours, but with an ozonator on most of the time it will drop by at least 50% or more.  Ozone reacts with chlorine to produce chloride and chlorate.  Or you can spend extra money and get an ozone test kit (yes, that's $5.95 for a SINGLE test).

[AaronSantaCruz]

I will stick with an ozone based system as I agree it better suits my purposes. Thank you again for all of your help. Now, I have another dilemma. I just spoke with a hot tub repairman that has been in the business for a long time and told me to avoid Hot Springs and Dimensions One, the two brands at the top of my list. Sounds like they are so packed full of foam that it is difficult to track down leaks and gain access.

[Tman122]

To me it sounds like he is affiliated to a different brand that doesn't fully insulate. Both those brands while yes, harder to repair if a leak develops in the foam, are known for not leaking in the foam. Yes it can happen but I would not base my purchase decision on that. If a particular brand was know for developing leaks in the foam and costing an arm and a leg to repair they would be long gone. I've disposed of 20 or more year old spas of those brands that never leaked in the foam. I've also repaired leaks in foam on tubs only 8-12 years old. Mostly freeze conditions. But they are not very common. More likely leaks in the equipment bay. And insulation has nothing to do with that.

[Spatech_tuo]

I as well would recommend a fully insulated spa that saves you on monthly energy costs and also is known for quality, including a low incidence of leaking. Hot Spring and D1 are certainly in that category.

[Tman122]

I as well would recommend a fully insulated spa that saves you on monthly energy costs and also is known for quality, including a low incidence of leaking. Hot Spring and D1 are certainly in that category.

And you got twice as many post's as me smarty pants.

[Spatech_tuo]

I as well would recommend a fully insulated spa that saves you on monthly energy costs and also is known for quality, including a low incidence of leaking. Hot Spring and D1 are certainly in that category.

And you got twice as many post's as me smarty pants.

You're just shy!

[AaronSantaCruz]

At first, I thought it would be useful to get the perspective of a local repairman, but then realized that there are many biases. For starters, they only see the problem tubs and not all of the functioning ones which get discounted in their viewpoints. They also tend to see the brands that are sold locally. I am considering a D1 brand which is sold 60 miles from where I live. I wonder if this will be problematic in having it maintained?