Chlorine from dosing tank

[A_kraker99]

I had another post with concerns that my daily chlorine usage seems way too high, but I guess I may just be at the high end of normal based on responses to that post. To maintain my levels I have to add about 4 PPM per day.
That got me thinking. I have a pentair dosing tank that is somewhat translucent plastic that sits in the sun half of the day. Is it possible that the sunlight is reducing the effectiveness of my 12.5% chlorine as it sits throughout the week?

 

[ajw22]

How long does the chlorine sit in the tank?

12.5% does not stay that way for long. It begins losing strength once bottled.

Breakdown of Bleach Over Time by Storage Temp - Further Reading

www.troublefreepool.com

 

[Richard320]

Good call. UV light is the enemy of bleach.

I figure your 12.5% stuff will be a little above the green line. But that's full sun, and yours blocks some. A couple years ago there was a thread where the guy actually buried his tank to keep it cool and he put a cover over it to block the sun.

 

[Brett S]

I keep staring at it, but I do not understand that graph at all. The bottom axis is ppm CYA and as near as I can tell it’s showing that the higher the CYA level the more chlorine is lost to UV per hour. But I thought that the whole point of CYA was to slow chlorine loss from UV. What am I missing here?

 

[Richard320]

I keep staring at it, but I do not understand that graph at all. The bottom axis is ppm CYA and as near as I can tell it’s showing that the higher the CYA level the more chlorine is lost to UV per hour. But I thought that the whole point of CYA was to slow chlorine loss from UV. What am I missing here?

I must agree with you. I seldom use that graph, so I never noticed before, but I think it's labelled wrong. Maybe you can make more sense from the text. It's in this thread Pool Water Chemistry