Split from another thread for better visibility.
OK, so last year definitely had some organics going in the pool did the shock treatment many times, drained water to get CYA down from 120's, etc, etc.
This year, Pool has been open about 30 days, Intellchlor 40 is running at level 5 and my FC is 2.5, no CC, CYA 70, PH 7.4, total alk 180 (little high). That is the readings from my test kit.
Pool water is 83. Pool water clarity is great, no visible signs of issues around the pool, no debris, etc. The lights were left out over the winter and there's no debris coming off the housing when I brush them (unlike last year).
Up until late last year I ran the IC 40 at 3 and never had a problem. I have taken off the IC 40 and it is producing chlorine (foams).
Thoughts here? Im pretty shocked that this pool is not holding chlorine.
Thanks
There have been a few pool users who reported seeing algae when their SWG pools were at 2 ppm FC so I would say that 3.2 ppm FC is closer to the correct number in the 70 ppm CYA range (though doing things like regular brushing might help one run at a lower FC level since the main problem is for algae stuck to surfaces that don't pass through the SWG cell to get superchlorinated and killed). There are even some SWG users where even 3 ppm was not enough, but that was for mustard/yellow algae (if I recall correctly). Because of the variety of factors that affect algae growth, including temperature and nutrient (phosphate, nitrate) levels, any recommendation is going to be something that works in most, but not all, situations. Ben's original chart was his "best guess" based on experience and knowledge and works for almost every pool for green algae prevention (mustard/yellow algae prevention needs closer to his Max column to prevent). I just translated such experience into consistent chemistry based on what is known about the disinfecting chlorine level at various FC and CYA levels.
The Pentair recommendation probably comes from the pool industry "standard" recommendation of 1-3 ppm FC that more recently has been changed to 2-3 ppm FC (I think -- could be 2-5) as the recommended range, but that standard says nothing about chlorine as a function of CYA. A new standard is apparently being developed (see this link), but I doubt that it will be any better regarding any discussion of Free Chlorine relative to CYA as the industry continues to point to the Pinellas study (that I discuss in this thread) as to why CYA doesn't matter.
You are welcome to try 2 ppm FC and let us know if your pool remains crystal clear, but with algae the recommendation has to be based on the chlorine level relative to CYA that has virtually all pools be free of algae. If some pools can operate with less chlorine, that's nice, but not useful as a general guideline.
Richard
OK, so last year definitely had some organics going in the pool did the shock treatment many times, drained water to get CYA down from 120's, etc, etc.
This year, Pool has been open about 30 days, Intellchlor 40 is running at level 5 and my FC is 2.5, no CC, CYA 70, PH 7.4, total alk 180 (little high). That is the readings from my test kit.
Pool water is 83. Pool water clarity is great, no visible signs of issues around the pool, no debris, etc. The lights were left out over the winter and there's no debris coming off the housing when I brush them (unlike last year).
Up until late last year I ran the IC 40 at 3 and never had a problem. I have taken off the IC 40 and it is producing chlorine (foams).
Thoughts here? Im pretty shocked that this pool is not holding chlorine.
Thanks