Chlorine levels

[mkymitts]

Hey all . Now I know this has been most likely covered a bunch but I am having a terrible time keeping the chlorine levels where they should be in my tub.  It never seems to be to high but always to low. Now my tub sits in direct sunlight all day long so I am sure that with the combination of that the the temp of the water it can not help. Or am I wrong? Any help on trying to stabilize this would be appreciated. All other levels are good. Thanks

[Topline Mike]

I would say you are correct.  Sunlight eats chlorine.  Is your tub connected to your pool?  Is that why you don't have a cover? 

[mkymitts]

Hey mike thanks for answering. No my tub is not connected to the pool. I do have a cover on it and for the life of me can not figure out why i seem to always be adding chlorine. Any suggestions would be appreciated.

[dunecritter]

Temp related...The hotter the water is the faster the chlorine gasses out and is not measurable. Using a stabilized chlorine is best and adding CYA will slow down the Gassing effect. Typically you can add chlorine after a soak and within 48 hours it will show no measurable levels of chlorine (Non Stabilized or no CYA added). That's why its important to shock every week even if the tub is not being used...If you add bottled chlorine everyday so you showed levels of sanitizer all times without the aid of a CYA I would say you were using way too much chlorine. It's normal for it to go away for the most part between soaks given 3 or 4 days between those soaks.
Chemgeek can better explain...I'm just a nobody

[chem geek]

That was a fine explanation.  The only thing I'd add is that ozone depletes chlorine so if you have an ozonator you probably won't be able to go 3-4 days without adding chlorine.  With an ozonator, you'd probably have to add chlorine every day or two.  So that's OK if you use the spa every day, but not so good if you only use it on weekends.

You can easily get CYA in the water by using Dichlor as your chlorine source, at least until you've built up the CYA to 30-40 ppm.  For every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm.

[UrbanUtah]

Hello, we recently installed a Saltron Mini Saltwater Chlorine Generator system in our 550 gal hot tub.  We have it turned up to 7 hours a day and still not registering any free chlorine.  PH and Alk are perfect, water used to re-fill the hot tub was filtered so the water is crystal clear.  We've had the system up and running about 3 weeks now and the free chlorine test strip still registers nothing.  Please help.

[UrbanUtah]

And just to add to my last post.  We've only used the hot tub once since switching over the system and we have not added any stabilizer (cyanauric acid) because the hot tub is covered and not exposed to sunlight.

[chem geek]

Cyanuric Acid isn't just to protect chlorine from breakdown from sunlight.  It also significantly moderates chlorine's strength.  If you use chlorine and have no CYA in the water at all, the chlorine will be too strong and oxidize swimsuits, skin and hair faster, outgas faster, corrode hot tub covers and equipment faster, etc.