Switching from bromine to chlorine

Sjde

Well-known member
Apr 29, 2016
280
Denver CO
We are thinking of switching from bromine to chlorine in our hot tub in a rental.
Will we always have to worry about/measure CYA or does it depend on what is used?
If I am not ready to start using bleach, are chlorine tablets okay, or granules in a cartridge?
The person at the store told me never to use chlorine meant for a pool in a spa-it'll ruin it.
I found this online-

Hottubsreport.com

" It is not safe to use chlorine meant for a swimming pool in your hot tub. Luckily, you can quickly tell the difference between the two by the nature form they are sold. A majority of swimming pool chlorine is in liquid form, popularly called sodium hypochlorite.
However, trichlor tablets are chlorine tablets meant for the pool as well, but they are not recommended for your tub. The tablets take longer to dissolve and can do significant damage to your tub’s acrylic shell or leave a permanent ring around the tub’s waterline. Chlorine tablets made of calcium hypochlorite are also a no-go for hot tub’s use. It doesn’t respond well to heat and can cause pH imbalance.
If you are going to choose chlorine tablets for your hot tub treatment, opt for sodium chlorine or di-chlor. The latter is the most recommended, although it could be a bit pricier than other options. However, you will have to keep testing your chlorine levels frequently since di-chlor does not come in the form of sanitizer cartridges or time-release tablets. Granulated chlorine is also a great option."
I can't seem to find sodium chlorine tablets anywhere.
Any help is appreciated!
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
5,834
Southern OK
Di chlor can be used at first to get CYA and chlorine in your spa but you stop using it once your CYA gets to 30...

Then you change over to Liquid chlorine or a Salt Water Generator to keep the chlorine in your spa... :)

For you I would HIGHLY recommend you switch over to a SWG, it is easy to keep in the spa and makes chlorine for you all the time :)


 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,498
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Will we always have to worry about/measure CYA or does it depend on what is used?
We recommend 30 ppm of CYA in a spa. It buffers the harshness of the FC.

If I am not ready to start using bleach, are chlorine tablets okay, or granules in a cartridge?
Nope. There are no tablets to my knowledge that work in a hot tub, all dissolve too quickly. Same with granules (dichlor). Dichlor dissolves super quick. Your options are manual additions of sodium hypochlorite (bleach/liquid chlorine) or dichlor. If you want constant additions then I agree with @cowboycasey, get a SWCG like the Saltron Mini. We both have the Saltron Mini, btw, so we aren't recommending something we don't use.

Hottubsreport.com

" It is not safe to use chlorine meant for a swimming pool in your hot tub. Luckily, you can quickly tell the difference between the two by the nature form they are sold. A majority of swimming pool chlorine is in liquid form, popularly called sodium hypochlorite.
However, trichlor tablets are chlorine tablets meant for the pool as well, but they are not recommended for your tub. The tablets take longer to dissolve and can do significant damage to your tub’s acrylic shell or leave a permanent ring around the tub’s waterline. Chlorine tablets made of calcium hypochlorite are also a no-go for hot tub’s use. It doesn’t respond well to heat and can cause pH imbalance.
If you are going to choose chlorine tablets for your hot tub treatment, opt for sodium chlorine or di-chlor. The latter is the most recommended, although it could be a bit pricier than other options. However, you will have to keep testing your chlorine levels frequently since di-chlor does not come in the form of sanitizer cartridges or time-release tablets. Granulated chlorine is also a great option."
This...this makes my head hurt. There is a tiny bit of truth here. You don't want to use trichlor or cal-hypo tablets in a hot tub as I previously mentioned, they would dissolve too quick. However, there is ABSOLUTELY NO REASON that liquid chlorine (sodium hypochlorite) cannot be used in a hot tub. In fact if you don't have a SWCG it's better than straight dichlor, as only using dichlor can build up too much CYA over time leading to ineffective sanitation.

I can't seem to find sodium chlorine tablets anywhere.
That's because sodium chlorine is not something that exists. Off the top of my head the following forms of chlorine can be used (you can skip all the following if you're not interested in nerd details):
  • Chlorine gas injection: Cannot be used in residential setups, used in some commercial pools as it's cheaper at scale than other forms of chlorine.
  • Saltwater Chlorine Generator (SWCG): These use a small amount of salt in the water and electrolysis to produce small amounts of chlorine gas, which is immediately absorbed into the water. These are commonly used in residential applications and provide a continuous production of chlorine, saving a lot of manual chlorine additions.
  • Calcium hypochlorite (cal-hypo): Sold in granule or tablet form. Adds calcium along with chlorine, which can result in buildup of too much calcium over time. Tablets not suitable for use in hot tubs.
  • Dichloro-S-Triazinetrione (dichlor): Sold in granule form. Adds CYA along with chlorine. Some CYA is useful, too much CYA can be problematic. Mildly acidic.
  • trichloro-s-triazinetrione (trichlor): Sold in tablet or granule form. Adds CYA along with chlorine. Some CYA is useful, too much CYA can be problematic. Tablets not suitable for use in hot tubs. Much more acidic than dichlor.
  • Sodium hypochlorite (bleach/liquid chlorine): Sold as a liquid only. Adds only sodium along with chlorine (a neutral additive). Cheap, readily available. Suitable for both pools and hot tubs.
Special mention:
  • Lithium hypochlorite (lithium-hypo): Sold in granule form. Global production of lithium batteries has make this very expensive. I personally suspect it will be completely unavailable in the future. Adds lithium along with chlorine, which was a neutral additive that made this form of chlorine attractive in some cases.
 

Sjde

Well-known member
Apr 29, 2016
280
Denver CO
I see Trichlor tablets sold and labeled for spa use, as long as they are 1” , not 3”. A friend of mine uses them in hers . We both have vacation rentals so we need something that has staying power and doesn’t need frequent additions to keep the sanitizer level adequate.