Ozone / UV / Salt Purification Systems

[HotTubster]

Researching our first hot tub. So many options!

Any thoughts on the best way to go for purification?
Ozone? UV? Salt? or some combination? Or no systems and just a good chemical-based only process with regular maintenance

Looking to minimize the use of chlorine.

What about the in-tub salt systems like the Saltron mini?
The use of salts & minerals sounds like it may add extra benefits

Will be a smaller spa used by 2 adults, 1/2 - 2 hours daily and occasional guests (up to 5 in tub)


Thanks!

[Dr. Spa™ Ret.]

salt = chlorine

[HotTubster]

Ok, I see salt is basically a slow chlorine release system, but also can harm components in the hot tub (like the heater).

What about ozonators and UV?
Is one better than the other? Can they work in tandem?

Thanks!

[av8r]

Ok, I see salt is basically a slow chlorine release system, but also can harm components in the hot tub (like the heater).

What about ozonators and UV?
Is one better than the other? Can they work in tandem?

Thanks!

I went through this recently for our 3 person tub.  Decided that KISS is best for us.  Dichlor to start and then switching to the BBB method.

The fewer things that can break, the better.

[d00nut]

All my personal tubs have had ozone.  In terms of Ozone and UV, they don't break... at least I have never heard of that.  They are stupid simple.  They do have a finite life though.  UV bulbs have to be replaced every year or so since they tint.  The Ozone unit are typically Corona Discharge, and most will last 3-5 years.  Depends on the type you use.

I just find that my water doesn't go south on me if I don't pay attention to it if I got a good ozone system in there.  If I don't have one... I got to babysit it a bit more.  It's more of a convenience thing for me though.

[chem geek]

Ozone reacts with chlorine so if you aren't using the tub every day or two then your chlorine demand in between soaks will likely be more than double and that means having to add chlorine every day or two.  On the other hand, if you use the tub every day, then ozone will oxidize some of the bather waste lowering chlorine demand.  So for a high bather-load spa, an ozonator makes sense, but for one used just on weekends or a couple of days a week, it doesn't.

[av8r]

All my personal tubs have had ozone.  In terms of Ozone and UV, they don't break... at least I have never heard of that.  They are stupid simple.  They do have a finite life though.  UV bulbs have to be replaced every year or so since they tint.  The Ozone unit are typically Corona Discharge, and most will last 3-5 years.  Depends on the type you use.

I just find that my water doesn't go south on me if I don't pay attention to it if I got a good ozone system in there.  If I don't have one... I got to babysit it a bit more.  It's more of a convenience thing for me though.

Your experience is backwards based on what Chemgeek has said about Ozone, but maybe I'm misunderstanding it.

I could have used a better word...perhaps "break" is not appropriate.  Having to replace a UV bulb each year or replacing an Ozonator every 3-5 years is more things to maintain and spend cash on.  I think I'll do OK without them and will save money as well.

[d00nut]

Nature 2 + Ozone + MPS.  I shock with Chlorine once a week.  Been doing that for the past 20 years.  Ozone does eat the Chlorine up, but I don't put that much Chlorine in my spa

[chem geek]

What he is saying is that with an ozonator the tub doesn't go south if the tub is not used.  What may happen in this case is that the ozone does deplete the chlorine in between soaks but that the ozonator is on enough to leave some residual ozone in the water and that keeps it from going south.  The problem is that for this situation the ozonator has to be on fairly frequently and it has to be fairly powerful, but that means excess ozone will outgas and that will degrade the hot tub cover faster and be harsh on other spa components.

So an ozonator is a delicate balance.  If it's strong, then it depletes chlorine but may also leave some ozone residual (at least if it's on a lot of the time) so disinfects more often but being harsh on spa components.  If it's not as strong or running as frequently, then it depletes less chlorine but still depletes it faster than no ozonator, but doesn't provide enough of a residual so the spa can go south.  If there is no ozonator, then the chlorine lasts the longest and can keep the spa from going south.  We've seen all of these situations reported.  There are those with ozonators where the spa still went south.

The ideal scenario would be where the ozonator turned on right after a soak and was on long enough to oxidize most of the bather waste and then after an hour or so the ozonator would turn off and chlorine would be added and maintained as a residual in between soaks.  Unfortunately no spa system has been designed to do this.  If spas had a button that would turn on the ozonator for some period of time (an hour or two) then one could press that when done with a soak and could also add chlorine after their soak (if they didn't want to wait a couple of hours for the ozonator to turn off) and the remaining chlorine would then last longer after the ozonator turned off.  Doesn't seem so hard, but no manufacturer does this.

[HotTubster]

Thanks chem geek ... that explains it very well ....

Is there any such thing as an over-the-side or in-tub ozanator that you can put in after you're done your soak and have it run on a timer for a couple hours?

Then pull it out when you are ready to use the tub again?

Thanks.

[chem geek]

There are over-the-side saltwater chlorine generators such as the ControlOMatic Technichlor, but I'm not aware of any over-the-side ozone generators.  So long as there was decent circulation, it's not a bad idea.  It would have to have excellent mixing of tiny ozone bubbles into the water so that they don't just bubble right out of the water.

[HotTubster]

Do 24/7 low-flow secondary circulation pumps make a difference in keeping the water cleaner?

[chem geek]

No, not really.  Circulation alone doesn't prevent bacterial growth unless there is disinfectant in the water.