Can UVI help predict FC demand?

rjb1211

Well-known member
Jul 29, 2017
262
Harrisburg,PA
Pool Size
37000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
In a pool that has light bather use chlorine burning off due to UV rays is a large determinant of FC demand. Does that mean paying attention to the UV Index can give you an idea of when you need to adjust the output of your SWG?

I don’t mean trying to micromanage the output day to day. Instead I am thinking about when to adjust as we move from spring to summer to fall. I had my IC40 dialed in pretty good until a couple of weeks ago when we got into a heat wave with daily UVI readings of 8 to 10. I have adjusted the output to deal with it. Running it at this level is not going to cause problems if the demand drops for a few days and testing shows a temporary rise in FC. I am wondering if I can use the index to tell me when it is time to lower the output by when it is not spiking every day.
 
That's a reasonable assumption and proxy, for FC demand, but there are too many variables and shouldn't replace testing. Try it out for a while, keep it toward the top end of the range for your CYA to protect from catastrophe, and report back how it works! We'd love to know!
 
keep it toward the top end of the range for your CYA to protect from catastrophe, and report back how it works! We'd love to know!
Can confirm. Staying at the top of the range works AMAZING. ;)



Does that mean paying attention to the UV Index can give you an idea of when you need to adjust the output of your SWG?
Among other variables, the length of the day comes into play also. We may have plenty high UV at the end of Aug, but the days will be 2 or 3 hours shorter.
 
Nothing scientific to report yet but it does appear that the daily UVI has a correlation to FC demand. My locale has not had the super high readings recently and the FC demand is lower even though it has been hot.

The next week is supposed to go back to high UVI readings and I will report what I get when testing.
 
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