Hi. My pool has been eating through chlorine for the past month and I'm not sure what might be causing the issue.
Here are my pool specs:
size: 20x40 8.5 ft deep inground pool. 35000 gallons
filter: hayward sand filter
UV filtration unit
Avg Temp: 90 degrees
Since we keep the pool temperature high, I expect to run through chlorine faster, but this is almost instantly and it is a problem that has just occurred over the past month. I don't see any signs of algae and the last test we brought to the pool store didn't show algae was present. The UV system prevents most of this, so I woul be surprised if get bacteria.
We haven't been able to get the chlorine level high enough to superchlorinate with Lithium shock granules, so yesterday we purchased 8 gallons of liquid shock and put that in the pool. Around midnight, I added the final 4 gallons and 45 minutes later the reading using my taylor test kit was above the 5ppm limit on the test. By this morning, by FC was back down to .5 with a CC of 1.0. I have my chlorinator set to 4ppm, so it's eating through tabs, but never getting the FC high enough to get a reading.
The PH and Alkalinity won't budge either. PH is steady at 7.2 and alkalinity is holding at 180
My CYA is a bit high at 80
I have read that it might be ammonia in the water, but I don't have a way to test, and I would have though the liquid shock would have caused an increase to the CC reading as it bonded with the ammonia, but it hasn't changed.
Any help would be appreciated