Super high combined chlorine

[themaccs]

Janet,
All those things you mention are concerns I am trying to balance. I'm not sure I understand why I am losing so much chlorine during the day. I retested my night time loss again last night to be sure we aren't losing any at night - we put a jug of bleach in at around 9:30 to bring FC up to 8ppm, shut off the chlorinator (which we had put 3 pucks in earlier in the day and set it on low to try to bump up CYA to slow daytime chlorine loss), and tested at 11:00. FC was at 8.0, CC - 0.5. Tested this morning before the sun hit the pool (about 7 am) and it was still 8.0, CC - 0.5. We do get a lot of direct sun-light on the pool. We are in south central Kansas. The pool is a direct Southern exposure with the direct sunlight first hitting east end of the pool by about 8 - 8:15 am and the first shade hitting the west end of the pool at about 6 pm. That's nearly 10 hours of strong direct sunlight, and the last week or so has been in the 90's nearly every day, dry, and nearly cloudless. I have been assuming that has accounted for my continued high chlorine loss during the day despite stable FC levels overnight. I just ran another test ( it is now about 1 pm - so 6 hours after my last test) with the following results:

FC - 5.5
CC - tr
pH - 7.4
TA - 120
CYA - 50 ( I really have trouble reading that dot - but 3 different tests got the same result) (we did have to add quite a bit of water today due to evaporative loss - level was down to bottom of skimmers)

Pool is 19500 gallons "sport" pool - 18x36xaverage 4 foot depth (3 foot shallow end, 5 foot middle, 4 foot other end).

The other issue that puzzles me a bit is my continued tr-0.5 ppm CC - we have had it at shock level 2x since we stopped losing chlorine at night, water has been crystal clear for weeks now, but CC doesn't seem to change: usually just a trace during the day, 0.5 first thing in the morning.

Any thoughts out there?

Thanks again for being here.

[aylad]

I can't explain why the higher CYA works better for me, but it does. If I kept my CYA at 50, I'd be pouring stuff in the pool constantly, trying to keep it clean. The best I can suggest is that you up the CYa by 10 ppm, and see if that does anything to lower your chlorine loss. If so, then up it a little at a time until you get to the lowest level of CYA that will keep the chlorine in the pool.

The trace of CC you're seeing is probably just pollen or other airborne "stuff" that the chlorine is burning off--once the sun hits the pool, it will take care of the CC if it stays that low. Sweat, suncscreen, etc can contribute to it, too. That's why we wait until CC gets to 1 or higher before we recommend shocking the pool. As long as it's not staying above 0.5, and you are not losing chlorine overnight, then your usual chlorination will take care of it.

Janet