It's been a year with my new Florida plaster pool. I have always struggled to keep the chlorine in range. CYA at 60, chlorine at 6-8ppm. SWG is a Pentair SC40 rated for 40k gallons and my pool is 17K (set to 100% output). pump runtime is 9.5 hours. It drops by about 1 ppm every day until I hit around 2-3% and then I add the calculated amount of 11.5% liquid chlorine to it to get it back to 6-8ppm, and then the cycle repeats.
It's been a year like this, the only time I didn't have a problem was Dec/Jan when I turned the heater off (we normally keep the pool temp at 90). During those two months, the chlorine naturally got to 20ppm in a weeks. I turned off the SWG and let it drift down to 6-8%, then I set it to 40% and it maintained it fine. Pool temps were around 72 those months. Other than those two months, I am constantly supplementing with chlorine. I have done 3 SLAMS, twice because the pool went to 0 ppm before I caught it, and once just to see if it helps. Each time, chlorine was held at the right elevated ppm, and then allowed to slowly drift down. It took a few weeks to get back to 6-8PPM, but once there, the cycle continued.
I have the full test kit and I promise everything is in ideal range. A neighbor who has no issues helped me verify, and so did a local pool store. Other things to note, but I don't know if it matters: I added borates to see if that would help. My CYA drifts down without draining and I've hit 30PPM a few times, and I've had to add a few pounds to get it back up (about 3 times this year), and we keep a solar cover on the pool to help retain the heat. If I run the pump 24 hours, I'll notice a 1ppm chlorine increase the next day. Lastly, I have checked the SWG for proper output in many ways. It is cleaned regularly, I get the right hydrogen bubbles, and I've done water tests directly from the return line and chlorine levels were showing a few PPM greater than the intake.
Pool has always looked crystal clear. Do I need to just keep adding shock every few days, or is there a way to end this cycle? At this point, I'd even add a second SWG if the Pentair system could handle 2, and if I had the plumbing space, but I don't.
It's been a year like this, the only time I didn't have a problem was Dec/Jan when I turned the heater off (we normally keep the pool temp at 90). During those two months, the chlorine naturally got to 20ppm in a weeks. I turned off the SWG and let it drift down to 6-8%, then I set it to 40% and it maintained it fine. Pool temps were around 72 those months. Other than those two months, I am constantly supplementing with chlorine. I have done 3 SLAMS, twice because the pool went to 0 ppm before I caught it, and once just to see if it helps. Each time, chlorine was held at the right elevated ppm, and then allowed to slowly drift down. It took a few weeks to get back to 6-8PPM, but once there, the cycle continued.
I have the full test kit and I promise everything is in ideal range. A neighbor who has no issues helped me verify, and so did a local pool store. Other things to note, but I don't know if it matters: I added borates to see if that would help. My CYA drifts down without draining and I've hit 30PPM a few times, and I've had to add a few pounds to get it back up (about 3 times this year), and we keep a solar cover on the pool to help retain the heat. If I run the pump 24 hours, I'll notice a 1ppm chlorine increase the next day. Lastly, I have checked the SWG for proper output in many ways. It is cleaned regularly, I get the right hydrogen bubbles, and I've done water tests directly from the return line and chlorine levels were showing a few PPM greater than the intake.
Pool has always looked crystal clear. Do I need to just keep adding shock every few days, or is there a way to end this cycle? At this point, I'd even add a second SWG if the Pentair system could handle 2, and if I had the plumbing space, but I don't.
florida a cya of 60 is just barely enough. That’s shoulder season cya - peak season should work up to around 80ppm along with bumping up run time. Follow the 
