Super high combined chlorine

[aylad]

Hi, and thanks for the update--we like to hear the end result after helping people with their pools--we all learn from it!!

I don't remember where you live, but losing 5-7 ppm chlorine daily is an awful lot. I'm in northwest Louisiana where the air temps are in the high 90s (heat index in the 105 range due to the 97%+ humidity), and my pool is in full sun from daylight to dusk--and losing 4-5 on a very hot day with a big bather load of kids is still a lot for me. I intentionally run my CYA at 80-90 ppm for that reason--with my weather conditions, I found that I lose much, much less FC during the day with it that high than with it lower. I'm one of the few that does this, but in my climate it's necessary. I lose 2-4 ppm on a hot day with a pool full of kids all day, and 94 degree water.

It's really a decision you have to make, because if you raise it to the higher levels and it doesn't work out for you, then you need to drain/refill to lower it...but then again if you're in a similar climate to mine, you might find that you don't lose nearly as much chlorine to the sun.

If you've got trichlor in the pool now, and use the chlorinator while you're on vacation, you're going to end up at around CYA of 70 anyway, so try it at 65-70, keep track of how much you're losing, and if it's less than you're losing now, you might want to consider going a little higher. Just keep in mind two things: 1) with the trichlor, you need to keep a good eye on your pH because trichlor will drive it down, and 2) the higher CYA works well in my pool because it's open year round--remember what the CYA breakdown did to your pool in terms of CC when you opened this year, and consider that in your decision. Might be worth it to raise CYA during the summer but drain/refill before closing it for winter, or at least set it up so you can keep chlorine in it during wintertime to avoid the ammonia problem again.

Janet

[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