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Salt Water Chlorine Generators


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#1 mmelo

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Posted 21 October 2012 - 08:41 PM

Hi All,

I currently have a chlorine tub. Using the advice on this forum its running great! The only remaining thorn in my side is the requirement to sanitize regularly to keep the chlorine levels where they need to be. I tried the bromine method and while it worked fine I just don't like the smell and will not consider it again.

So I'm looking at 2 options:

1. A floater for chlorine tabs. I'm hesistant based on my bromine floater experience - always too high or too low as we use the tub irregularly it was difficult to set and forget.

2. Salt water chlorine generator. I'm not sure why there is so little information out there about these for spas. They appear to be the dominant sanitizer method in pools... I'm considering the Saltron Mini or the Nexa unit the other ones on the market seem to use less than honest marketing tactics. Whats the deal with these? Why aren't they the dominant sanitizer method for spa's as well? Why all the suspicison or hype? Who wonuldn't want an automated sanitizer?

Help me out folks what am I missing?

Thanks in advance!

Michael

#2 chem geek

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Posted 21 October 2012 - 09:03 PM

The most common from of disinfection in residential swimming pools is Trichlor tabs/pucks either in a floating feeder or in an inline chlorinator. Saltwater chlorine generators (SWCG) are popular for new in-ground pools, but less commonly seen in above-ground pools (though they do exist) which make up about half of all residential pools. Pool services tend to use Trichlor because they only visit once a week or two. Of course, we all know the problems that can occur when using Trichlor unless one uses supplemental products or dilutes the water to limit the CYA buildup. Chlorinating liquid or bleach is also fairly common; Cal-Hypo rounds out the rest.

The main reason that SWCGs such as ControlOMatic Technichlor are not more popular in spas is that the amount of chlorine needed in a spa varies a lot based on bather load while in a pool it's much more constant unless the weather varies. So for those that believe it's a completely automatic "set and forget" system, it isn't. Also, the higher salt levels that are required (2000 ppm for spas; 3000 ppm for pools) can increase corrosion rates, especially when the spa materials or circulation equipment did not use higher quality materials. Another issue is that the SWCG folks for spas haven't figured out that using chlorine with no CYA in the water is too strong/harsh so it ends up smelling more and oxidizing swimsuits, skin and hair faster and potentially corroding metals faster; obviously this can be easily mitigated by adding CYA to the water initially on each water change. Note that the ControlOMatcie Technichlor does have a "boost" mode you can use after every soak, but it may not be enough to handle your bather load if you soak for a longer time with more than one person, but you should check it out. Worst case, you can supplement with some chlorine bleach after a soak and use the SWCG for a background level of chlorine.

So check your spa manufacter's warranty to see what they say about using a saltwater chlorine generator and/or higher salt levels, but keep in mind that since you use the tub irregularly you will have the same problem with a saltwater chlorine generator as you did with your bromine tabs in terms of not being able to "set and forget". Quite frankly, there is no product or device on the market that will let you "set and forget" for spas, though there are expensive products that are close to that for pools that use ORP or chlorine sensors to vary chlorine dosing.

As for trichlor pucks/tabs, they dissolve too quickly in hot water unless they are in very special feeders and some spa manufacturers void their warranties if you use them, mostly because they are so acidic so it's more likely to damage equipment unless you adjust the pH without fail (of course, the pH adjustment requirement is also true for pools as well).

#3 mmelo

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Posted 21 October 2012 - 09:17 PM

Hmmm. Thanks for the info. I get that there is no true set and forget. Maybe I should have just asked how you folks deal with not being home for a period of time? We go away annually (budget allowing) for 2 weeks with trips throughout the year of anywhere from 3 to 7 days. How does one keep the tub chlorine levels up?

Thanks!

Michael

#4 chem geek

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Posted 22 October 2012 - 01:37 AM

If it's only for up to one week, you can lower your spa temperature (say, to 80ºF; just turn down your thermostat) and shock with chlorine. If you don't have an ozonator and your spa is covered (not exposed to UV in sunlight) and your daily FC loss was 25% when the temp was higher, then the loss may only be 15% at the lower temp. In that case, after 7 days you may only get down to around 1/3rd your initial FC level. Even with a 25% per day loss, you may end up with 10% of your original FC. Raise the FC to 10 ppm before you go and you should still have some FC by the time you return. Make sure you've got CYA in the water -- 30 ppm or more -- since that will reduce the rate of loss especially from outgassing (and reaction with the spa cover).

It's when people are gone for more than 1 week, so 2-3 weeks or more, that shocking becomes more iffy and not likely to keep the chlorine up.

#5 arches2

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Posted 22 October 2012 - 05:37 AM

Hmmm. Thanks for the info. I get that there is no true set and forget. Maybe I should have just asked how you folks deal with not being home for a period of time? We go away annually (budget allowing) for 2 weeks with trips throughout the year of anywhere from 3 to 7 days. How does one keep the tub chlorine levels up?

Thanks!

Michael

The Technichlor SWCG is a very good option for you. Like Chem Geek said it will take care of the background and does have a boost mode for lighter load soaks. Think of it as a floater in the bromine system. then if you get a spike in bather load occasionally you can just drop in a little bleach to suppliment. Very easy. Only $300 to implement. I may head in that direction eeventually but bromine is working for me. I do have a friend with one and he swears by it.




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