High Chlorine all of a sudden

[LBTRS]

My FC has been running right around 5 with my filter and SWG running for 8 hours per night at 40%. All of a sudden after this weekend my FC is at 10 and I can't get it down. I finally turned my SWG off and will leave it off until I get it down. Any idea why the chlorine level would rise with no other changes? Only thing I did this weekend is shock the pool with a non-chlorine shock (Fresh 'n Clear from Leslies) and add MA to lower the Ph from 7.8. Water looks great but you can smell chlorine when you walk into the backyard.

FC 10
CC 0
CYA 65
TA 90
Ph 7.5
CH 230
Salt 2900


Thanks for any help.

 

[JohnT]

With the FC at 10 and 0 CC, it seems really odd to me that you can smell the chlorine. The only plausible explanation I can offer is that you had a lot of contaminants in the pool which were consuming chlorine. When you used the shock, you eliminated them, which allowed the chlorine level to rise. I'm still puzzled by the chlorine smell.

 

[no-mas]

I experienced something similar last year around this time - I didn't shock like you did, but found my FC at 8 from the usual 3, and could slightly smell it. I've never detected CCs in my pool and have never shocked. I attributed it to decreased usage and cooling temperatures. I decreased the %output and the pump run time, which seemed to work after about a week.

The smell wasn't a nasty overwhelming odor - just a slight fresh scent of chlorine when I came close to the water, but that I had never noticed prior to or since. This year I've already decreased run time and SWG output, and have had neither the spike in chlorine nor the odor I detected last year.

 

[JasonLion]

If the water temperature has been falling recently the pool would use less chlorine, which could result in a high than normal FC level.

 

[LBTRS]

Thanks guys...maybe it's the cooler weather and I need to reduce my chlorine % and run time. I'll give it a try and let you know.