Salt Water Chlorine Generator in Cedar Tub

[ted1209]

I’m wondering if anyone has tried salt water + chlorine generator in a cedar hot tub. I’ve had a few sales people tell me that salt water will break down a cedar tub faster, but I’ve learned that hot tub advice from salespeople is all over the place. It seems cedar does fine in ocean water, which has 10x the salt concentration vs for chlorine generation.

 

I love the idea of the more plug and play of chlorine generation, but am looking for other opinions. I am thinking of using this unit: https://www.controlomatic.com/chlorinegenerators/smarterspa/

[RDspaguy]

I really couldn't say for sure. I have worked on a handful of wood tubs in my 25 years, but have only actually seen one spa on a salt system. 

In my opinion, it's not the salt that you should worry about, but the chlorine being generated. A salt cell creates a very high concentration of a strong oxidizer which is released into the tub. This does not instantly mix, so you have a swirl of bleach, following a predictable path around your tub and reacting with the wood. Even with some cya to buffer it, it takes time to mix, so doesn't really help the wood. Over time I would suspect this will cause some issues.

@waterbear do you any Insight on this?

[waterbear]

Not an expert on the subject but from what I've heard is that salt bromine generators are a better choice for wooden tubs because it is less aggressive on the wood than chlorine.  This also applies to sanitation with tablet or granule sanitation and not just salt generators.

[RDspaguy]

Bromine generators apparently have some health concerns and are illegal in some countries as a result. I do not recommend a bromine generator. 

[waterbear]

The only country where they are illegal, as far as I know, is Canada and I have read their reports and their evidence is shaky, Most of it is because of the formation of bromate, which is a problem in drinking water However, one does not drink hot tub water and any bromate that forms is easily taken care of by the peridic drains and refills that are part of tub maintenance and are usually done every 3 to 4 months. I find it interesting that they have only outlawed the use of sodium bromide in salt generators and in 2 step systems with MPS oxidizer. They said nothing about 2 part systems with a chlorine oxidizer not the use of 1-bromo-3-chloro-5,5-dimethylhydantoin or BCDMH (bromine tablets used in a floater) which is an organic bromine and chlorine compound which supplies bromine ions (just like sodium bromide) which are then oxidized into hypobromous acid by the included chlorine (much like using any of the common chlorine sources to oxidize bromine ions in a two step system). The formation of bromate is essentially the same in all cases. The use of ozone can increase bromate formation (and chlorate formation in a chlorine system) which is why I was never a fan of ozone, except perhaps in a saltwater fish tank, to increase redox potential of the water but that has nothing to do with hot tubs! (Been keeping reef aquaria since the 70s)

 

 

[ted1209]

Thanks everyone for your input on this. I noted that Dr Spa always recommended Chlorine for cedar tubs, and suggested to avoid ozone. Given this I think I am going to go for it with the salt water + Chlorine generator and see what happens. My only question is if I should get an ionizer. My current thinking is no, just go with salt + chlorine generator as it’s unclear how helpful ionizer actually is and seems like another cost + maintenance item, but I wanted to see what you all think. Would an ionizer be worth the cost + maintenance?

[RDspaguy]

Dr. who? 

That's a matter of opinion. To me, in an acrylic spa with ozone, it is worth it. 

[waterbear]

Personally I am not a fan of ozone.  It tends to increase bromate formation in a bromine tub and chlorite/chlorate formation in a chlorine tub. UV ozonator that run whenever the pump is on are the most common type and they really don't do all that much but they are inexpensive so manufacturers include them so they can say the tub includes an ozone generator.  Corona Discharge units are much better and the way to go if you wantcozone but they are usually aftermarket and expen$ive.

[RDspaguy]

I would not put ozone in a spa that was not plumbed for it. Ozone injection systems have a very long run of pipe before returning to the tub, sometimes several loops around the spa.

As I understand it, ozone is unstable once it leaves the uv radiation and will convert back to oxygen in about 20-30 seconds at sea level. I have even heard that it is this conversion, and the resulting free radical O(1), that actually does the oxidation and not really the ozone at all. So to get the full benefits of ozone you must keep it in contact with the water in the pipes until it converts. Releasing it directly into the tub does little for the water, but will destroy your cover in no time as the ozone builds up underneath it and goes to work on the moisture barrier in your cover. In a wood tub, that would also be the exposed wood above water level.

I can say from personal experience that early ozone systems ate up covers, with no doubt. But the rest is hearsay.

[waterbear]

19 hours ago, RDspaguy said:

I can say from personal experience that early ozone systems ate up covers

and had a detrimental effect on some plastic jets, not unlike biguinde (which I always suspected was not so much from the biguinde but from the peroxide oxidizer used in conjunction with it). UV system really don't generate enough ozone to do that much but they are inexpensive for a manufacturer to include and say the tub has ozone. Corona discharge systems are much more expensive so manufacturers tend not to use them because they would increase the cost of the tub beyond what people might want to spend or make the tub seem like a bad value compared to one using UV. The consumer is only going to see that brand x and brand y both have ozone but brand x is much less expensive and not realize that they are really trying to compare apples and oranges.

[waterbear]

19 hours ago, RDspaguy said:

I would not put ozone in a spa that was not plumbed for it. Ozone injection systems have a very long run of pipe before returning to the tub, sometimes several loops around the spa.

This is because they don't use reaction chambers and are trying to make sure all the ozone is gone before the water enters the tub. Ozone is toxic and can damage lungs.

"Ozone systems in portable hot tubs utilize:

A device that injects raw ozone gas directly into the water stream

Most portable hot tubs do not use an isolated ozone mixing chamber

If you can smell ozone bubbling up inches from your nose while you're soaking in your tub you are breathing raw, undissolved ozone gas

Very few portable hot tubs have ever used ozone mixing or reactor chambers and even fewer have ever used de-gas valves or ozone destruct units.

Most portable hot tubs equipped with ozonators inject ozone gas directly into the water stream. If you can smell ozone while soaking in your tub you are breathing raw, undissolved ozone gas."

http://affordablehottubrepair.com/unfiltered-truth-about-ozone-in-hot-tubs.html

[waterbear]

20 hours ago, RDspaguy said:

Dr. who? 

Dr. Spa. He used to be a Mod here. Still listed as one but haven't seen him on here in a while. Guy knows his stuff!!! He owns Robert's Hot Tubs if I am not mistaken, which specializes in wooden tubs.

[RDspaguy]

In my experience, almost all the early ozonators were uv (bulb) type (except cal spas). I didn't know anything about them at the time, but they worked well enough to destroy covers in alot of spas before they figured out not to connect the ozone tube directly to a jet air intake.

D1 used an air bellows pump (like a fish tank aerator) to push the ozone through a diffuser bulb and up a pipe, thereby creating the water flow for the heater as well, inside of a filter sized canister with a 6" thick activated charcoal vented lid to filter the ozone out and release the air. The uv ozonator was actually inside of the control pack above the circuit board. The bellows would frequently fail, and the output tube nipple was prone to breaking, both of which resulted in ozone in the control box. I can tell you that ozone will destroy a circuit board too. They had a good plan, but failed miserably in the implementation. 🤪

Most modern spas (that I have seen) have some type of mixing chamber or long pipe run for the ozone. 

11 hours ago, waterbear said:

breathing raw, undissolved ozone gas.

I knew a guy who took a job selling "ozone air purifiers" many years ago. They were like a tall space heater that made ozone instead of heat and blew it out into the room. He was given a unit as part of his sales kit, and decided to try it out. He had it running and fell asleep watching tv, then later went to bed having forgotten the ozone purifier was running. The next day he had lost his voice, had a sore throat and breathing difficulty, and red and swollen eyes. His voice did not return for a week. It was kinda nice for me, as he previously never shut up.😉