izjay said:Ohm_Boy said:In addition to the loss from killing organics, there will be some percentage of loss during the day to UV. As a percentage, the UV loss is greater at higher FC levels, so more of the higher levels are wasted during the day. I doubt that the higher levels are physically hurting anything, since this isn't a vinyl or fiberglass pool, but it would probably be best to stay around the shock/mustard shock level, from an economy POV.
My pool (salt) has a CYA of around 60. I see on the CYA/Chlorine chart that the shock level is 30. Is there a different level for mustard algae or is 30 what I should be shooting for? Over the past couple of days I have been trying to keep the FC level in the upper 40's (just to hit it hard) and it takes over two gallons of chlorine a day to do this. Yesterday, I started the day at FC 39 and added chlorine (almost 3 gallons) throughout the day. It went up to as high as 51, but dropped back down to 41 by this morning.
From the CYA/chlorine chart in Pool School, with a CYA of 60, the shock level is FC of 24ppm {30 is for CYA of 80}.
According to poolcalculator.com, with a CYA of 60, the shock level is FC of 18ppm with a Mustard shock level of 34ppm.
The pool school chart is a little more aggressive for normal shock levels, but does not indicate anything for Mustard shock level.
In any case, there is no source that is recommending going much over 34ppm and as previously indicated, you will see more UV loss the higher FC levels you attempt to maintain.