SWG in a hot tub - worried about corrosion on the heater

[mjc123]

I've got a brand new Master Spa tub, and I'm researching the idea of using a SWG in it. The sales person told me it's not a good idea in hot tubs because the heat exacerbates the corrosive effect of chemicals (salt in particular) on the metal parts, which is primarily the heater, obviously. That said, I also don't trust pool/HT sales people based on my experience and already this guy has made false claims to me already. The SWG for my pool is amazing so I wish I could have the same experience with the HT, but I don't want to have to replace the heater/element in a year.

I've seen several posts on this site about SWGs in hot tubs, including several posts about heating elements rusting out. However, I haven't seen any "definitive" answers about whether SWGs are safe or not. Several people appear to have switched to titanium elements, but I haven't seen any follow up posts commenting on how that has worked out. Perhaps I've just missed them.

 

[Mdragger88]

It is recommended to have a titanium heater if you have a choice. The tubs that come with swcg’s usually have this.
I have no idea what mine is made of but it’s 5 years old & i have used a saltron mini since i got it.

 

[mjc123]

It is recommended to have a titanium heater if you have a choice. The tubs that come with swcg’s usually have this.
I have no idea what mine is made of but it’s 5 years old & i have used a saltron mini since i got it.

hopefully something as easy as this?

Balboa 5.5kW M-7 Universal Flow Thru Element, Titanium

Balboa 5.5kW M-7 Universal Flow Thru Element, Titanium The Balboa Titanium heater element will heat your hot tub with out the worry of scale build up due to the unique coating. You will see that the Titanium coating on the heater element will help to transfer more heat to your hot tub water that...

www.poolstorecanada.ca

I'll have to look up whether that's compatible with my heater, but looks easy enough assuming I can just drop it in

 

[Jimrahbe]

123,

Hot tub heater failures are pretty normal to see. I doubt that there is any difference between having saltwater or not, but I have no proof that is true.

Thanks,

Jim R.

 

[Mdragger88]

I wouldn’t replace my heater in advance because something “might happen”. Spa heaters simply don’t last forever.
Doing this would also likely void your warranty if you’re concerned about that.
In the master spa warranties I read (not sure which one you have) there is no mention of salt or a swcg - the only thing mentioned is that the only approved sanitizer is dichlor which is fine up to a few doses then cya gets out of control so TFP recommends that liquid chlorine & or a swcg should be used after cya reaches around 30ppm.
FC/CYA Levels

How do I use Chlorine in my Spa or Hot Tub?

If you have a question about any information within this Sticky, please start a new thread for yourself where you will receive very quick responses to your specific questions. Thank you! Introduction There are two main things to consider when maintaining your hot tub water, Water Balance and...

www.google.com

More often than not the cause of corrosion/scaling/damage in a spa or any heater (like in a pool) has more to do with mismanagement of ph than the salt level.

 

[mjc123]

I wouldn’t replace my heater in advance because something “might happen”. Spa heaters simply don’t last forever.
Doing this would also likely void your warranty if you’re concerned about that.
In the master spa warranties I read (not sure which one you have) there is no mention of salt or a swcg - the only thing mentioned is that the only approved sanitizer is dichlor which is fine up to a few doses then cya gets out of control so TFP recommends that liquid chlorine & or a swcg should be used after cya reaches around 30ppm.
FC/CYA Levels

How do I use Chlorine in my Spa or Hot Tub?

If you have a question about any information within this Sticky, please start a new thread for yourself where you will receive very quick responses to your specific questions. Thank you! Introduction There are two main things to consider when maintaining your hot tub water, Water Balance and...

www.google.com

More often than not the cause of corrosion/scaling/damage in a spa or any heater (like in a pool) has more to do with mismanagement of ph than the salt level.

out of curiosity, why a recommendation of CYA at 20-30 at all? (ie, why not simply 0, given that a hot tub is generally not exposed to UV?)

 

[BDY]

Chlorine with 0 cya is incredibly harsh … you need some small amount of cya to buffer it

 

[Mdragger88]

What he said
Also it makes it very hard to maintain adequate residual fc since the bather load is so high due to it being such a small body of water.
the minimum fc should ever be is 2ppm, with no cya fc above 3 ppm is harsh so that leaves you 1ppm of wiggle room and in a hot tub with 2 people that can be gone in a flash (under 30 minutes) opening the door for person to person transmission of pathogens & funky stuff proliferating at a rapid pace
1 person in a 400 gal hot tub is like 50 people in a 20k gal pool. Its like a frat party for every use.

Chlorine/CYA Chart

EDIT: You will find a simplified and standardized version of this chart at Pool School, Chlorine / CYA Chart. Chlorine/CYA Chart by Chemgeek FC = Free Chlorine in parts-per-million (ppm) CYA = Cyanuric Acid in parts-per-million (ppm) CYA ........... Min FC3 ..... Target FC ...... Yel/Mstrd...

www.troublefreepool.com

 

[wayner]

Chlorine with 0 cya is incredibly harsh … you need some small amount of cya to buffer it

I have had a drapeover SWCG for 3.5 years and haven't had that issue. I keep my FC around 1.5-2.

 

[wayner]

I am pretty sure that I have seen studies with swimming pools on this forum that show that saltwater is no more corrosive than chlorinated water. Chlorine is pretty corrosive stuff on its own.