Relocated from this post by Moderator
Just an opinion from a non expert here, but I find the SWCG manufacturers' recomendations for CYA to be too high. 70 or 80 ppm is fine until all **** breaks loose. Just look at how much bleach you need to add to a 25-30K gallon pool to address the problem after it develops. Forget the cost...how about the running back and forth to Walmart or Costco and hauling all those bottles around. How about the time wasted baby sitting that swamp. I never let my CYA get above 50. Actually, I prefer it around 40-45. I can run my SWCG at 30% and maintain 4-5 ppm chlorine all summer long. Now, I live in southern NYS, and YMMV in warmer climates.
It seems to make more sense for the CYA levels to be determined not by some seemingly arbitrary number, but by how long you must run your SWCG...at say 30 to 40 %( I'll let the experts debate the appropriate amount of time to run the cell). Admittedly, arriving at the correct CYA for your pool may take some time and is probably not something the average pool owner wants to be bothered with...but in the long run will probably save significant time and money clearing a green pool with a CYA of 80.
Hope your swimming soon!