Can't Lower Cl Level

[matthewnadeau]

I have a 15K gallon in-ground pool and I can't get the Cl level to drop. It's been over 20ppm for about 2 months and I haven't added any Chlorine during that time.

I use 3" tabs in the skimmer and I alternate in with liquid CL about every 3 or 4 applications. I shock the pool with 68% Calcium Hypochlorite about every 2 or 3 weeks during the summer and about once per month in the winter (we're in Northern California, so the winter is short)

I have also been trying to lower my Cyanuric Acid level (I assume that it's tied in with the high Cl) - I've been over 100ppm since August and I've drained my pool down ~6" three times now without any significant reduction.

The rest of the readings are within normal range: pH = 7.6, Alkalinity = 70 - 80, Ca Hardness = 400 - 450.

Besides draining the pool a few more times, is there anything else I should be doing?