CYA or no CYA in spa with SWG?

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Razorhog

Razorhog

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Jun 20, 2013
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Northeast Arkansas
I'm getting a Hot Spring Spa with the built in SWG. They call it the Freshwater Salt System. They don't talk a lot about CYA in the Salt System Owner's Manual, other than to say that you should try to avoid CYA (Chlorine) lock. I did find the Dealer's FAQ that says the preferred level of CYA is zero, but up to 50ppm is fine. Sunlight generally won't be a factor because this is a portable/standalone spa with a cover. It might be used when in broad daylight occasionally but not much.
After reading the stickied post about using Chlorine in a tub, I feel like I should have some CYA in the water but I'm not sure.
The Owner's manual says the suggested levels of chlorine is 1-5 ppm with a target of 3ppm. That seems excessive if there is no CYA in the water.
The SWG on these tubs is miniscule and doesn't produce much chlorine, so should I just skip the CYA?
 
I have the same system. When I start up the tub I use dichlor for the first few times I need to add chlorine so that I build up some CYA- I aim for 20 ish. After that, if I need to add I use plain bleach. You will find the system works best if you find a setting that keeps your chlorine where you want it, then if you use it for a long time or with multiple people, you will need to add chlorine as it won't keep up. If it is just my wife and I, we don't need to add. If the kids get in I add bleach afterwards. Hope this helps.
 
No.

if you read the forum sticky on chlorinating a hot tub, 30ppm CYA is recommended. Why? Because the harshness of active chlorine compounds needs to be buffered. Water with 1ppm FC and zero CYA has about 15X as much hypochlorous acid in it than water with 2ppm FC and 30ppm CYA. Both will adequately sanitize a hot tub but the water with 30ppm CYA will feel and smell much better.

It doesn’t matter what the source of chlorine is or, to a certain extent whether or not sunlight is present. Stabilizer (ie, CYA) is a necessary component of chlorinated recreational water.
 
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It is not needed, but you might want a bit for other reasons besides chlorine stabilization. Some claim that it is less irritating and changes the feel of the water.
CYA does not change recommended chlorine levels within the recommended range. Those levels are higher than a pool due to the temperature of the water evaporating chlorine faster and providing a better environment for bacterial growth than typical pool temperatures. Also, due to much lower water volume a spa is more rapidly depleted of sanitizer by use. 1 person in a 350 gallon spa is like 100 people in a 35,000 gallon pool.
 
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Thanks for the replies!

Backcountryski said:
I have the same system. When I start up the tub I use dichlor for the first few times I need to add chlorine so that I build up some CYA- I aim for 20 ish. After that, if I need to add I use plain bleach. You will find the system works best if you find a setting that keeps your chlorine where you want it, then if you use it for a long time or with multiple people, you will need to add chlorine as it won't keep up. If it is just my wife and I, we don't need to add. If the kids get in I add bleach afterwards. Hope this helps.
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That is especially helpful, thanks @Backcountryski - That sounds like exactly what I'll need to do.
 
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What is "dichlor"? I am new to hot tub.

Similar to the OP, I have a Hot Spring hot tub with SWG (SmarterSpa) and I haven't add any chlorine or CYA (stabilizer) yet.

So is safe to just add household bleach? How much would I put in for a 500 gallon hot tub? Also, which stabilizer do I put in and how much if I wanted to introduce CYA? I just started my hot tub for the first time last Friday. Less than a week experience with hot tub and I plan to start over by first purging the tub with Ahh-Some.
 
I have a 350 gallon Caldera with the same freshwater salt system. I started using dichlor in a heavily used tub and realized after using over half the small bottle that my CYA was nearly 100 in just a couple weeks when I found this site. I drained and have been using the dichlor/bleach method since then. Our tub is really heavily used now so I haven't found the SWG to keep up yet, but its very simple to just supplement with bleach after long sessions.

I'll probably do another drain and purge with ahhsome in a few months since I didnt' find out about that until after my first drain.
 
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Roaddogmm said:
I have a 350 gallon Caldera with the same freshwater salt system. I started using dichlor in a heavily used tub and realized after using over half the small bottle that my CYA was nearly 100 in just a couple weeks when I found this site. I drained and have been using the dichlor/bleach method since then. Our tub is really heavily used now so I haven't found the SWG to keep up yet, but its very simple to just supplement with bleach after long sessions.

I'll probably do another drain and purge with ahhsome in a few months since I didnt' find out about that until after my first drain.
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Can someone explain to me what "dichlor/bleach" method is? thanks
 
mmbiker said:
Can someone explain to me what "dichlor/bleach" method is? thanks
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It’s basically the sticky thread in the Spas & Hot Tubs sub-forum -

How do I use Chlorine in my Spa (or pool)?

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.troublefreepool.com www.troublefreepool.com

You start your tub by chlorinating with dichlor granules until you reach a CYA of 30ppm then you switch over to liquid chlorine for daily chlorination.
 
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Does the use of CYA differ if your spa is always covered? I have a Jacuzzi spa and I am about to switch from bromine to a Drape Over SWCG. Should I be worried about CYA? When it comes to pools I always thought that you don't use CYA in an indoor pool and I was thinking that a covered spa would be similar to an indoor pool as there is no UV or sublimation of Chlorine.
 
It definitely has an effect on the skin & equipment. Its also hard to adjust very tiny levels of fc that would be used if you had no cya as 3ppm w/no cya is quite harsh so I imagine shocking would be rough. Its called conditioner for a reason 😊 my swg also lists the need for it.
 
OK, good to know. I guess one minor problem is that it isn't very easy to measure CYA at a level of 30 with the Taylor test kit.
 
wayner said:
OK, good to know. I guess one minor problem is that it isn't very easy to measure CYA at a level of 30 with the Taylor test kit.
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Yeah, I can't measure it with my taylor kit either. I just measure out the amount of diclor needed to get toe 30ppm CYA from zero, and dose with it until it runs out on a fresh refil, and then switch to straight chlorine.
 
At spa temperatures, chlorine will oxidize about 5ppm CYA per month. To maintain your 30 target, you will need to add additional CYA via dichlor - especially if you go several months between water replacement. If you can't test it, just add the 5ppm CYA dichlor equivalent on a monthly basis.
 
Why use dichlor rather than straight CYA? I tend to have stabilizer for my pool and I keep liquid chlorine around just in case something is wrong with my SWCG. The problem is that the mass of CYA needed is rather small. According to Pool Math I need 30g of CYA to get from 0 to 30 in my 1270L spa. That is a pretty tiny amount. I added a bit and I am still below 30 so I tried adding around a tablespoon. Hopefully I didn't go too high. Testing for CYA is such a pain.
 
wayner said:
Why use dichlor rather than straight CYA? I tend to have stabilizer for my pool and I keep liquid chlorine around just in case something is wrong with my SWCG.
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I believe it's because most people with spas will have dichlor laying around, and so that method was used rather than buying an extra chemical. If you have CYA laying around, there's zero reason you can't use that.

wayner said:
According to Pool Math I need 30g of CYA to get from 0 to 30 in my 1270L spa. That is a pretty tiny amount.
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I got a small digital scale for like $10 off Amazon that can easily measure sub-gram levels. I use this for adding dichlor to my spa. Would work great for measuring out CYA as well.
 
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I use CYA instead of dichlor, since I have it for the big pool - I measured how much I need to get 30ppm and found a little screw top container that fits just that amount and I use it whenever I do a water exchange, or if my CYA degrades enough before a water change. I do the same thing with a bigger container to add just the right amount of CH to keep foaming down after each water exchange. I have to add enough chlorine to get to 6ppm and then I toss the SWG in the drink.

The PH and TA takes a little more time, with a ton of small doses of acid over several hours and days...
 
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