I drained over half the water in the pool over the weekend because of high CYA. CYA is now less than 30, probably less than 20 but the test tube only goes to 30. PH is about 7.1 and TA is 70. I checked free chlorine and it was about 2 so I added enough bleach to bring it to 12 ppm Sunday evening. I checked it this morning and I lost about 3 ppm overnight but I basically have no combined chlorine. I added more bleach this morning and brought it back to 12 and still have no combined chlorine. My pool is solid green and I can not see the bottom. Normally when I shock it the algae will turn a pretty blue by the next morning, not this time. Shouldn't I have quite a bit of combined chlorine with all the algae I have or am I not understanding what combined chlorine is? The filter has also all of the sudden stopped catching anything. I built this pool 3 years ago and it has been a headache from day one. I had a 30' above ground for several years and it never gave me trouble. I'm scratching my head on this one. Any ideas?
Combined chlorine question.
- Thread starter nxslt1
- Start date
- May 23, 2015
- 24,702
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Algae does not necessarily produce combined chlorine compounds when it is killed. Bather waste, sweat, urine, etc, are what typically create CCs. Green pools can sometimes convert CYA to ammonia (if the right bacteria are present) which would then cause a huge chlorine demand and very high CCs to get rid of. But "killing stuff" doesn't necessarily create CCs, chlorine oxidation of amine-containing compounds is what drives CC levels.
So does a drop of 3 ppm overnight mean I'm killing algae? I don't understand why it hasn't turned blue like it usually does.
- Mar 24, 2014
- 2,455
- Pool Size
- 32000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-55
If your filter isn't working it may be time for a deep clean Deep Cleaning a Sand Filter although that isn't going to kill the algae, chlorine will.
Some SLAMs take many days, sometimes weeks. I'm surprised you've gone green to blue so quickly in the past. If you close late and open early you may find you have a much clearer pool next Spring.
Some SLAMs take many days, sometimes weeks. I'm surprised you've gone green to blue so quickly in the past. If you close late and open early you may find you have a much clearer pool next Spring.
- May 23, 2015
- 24,702
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Are you following the SLAM process in Pool School? Are you actually testing the water to make sure you're hitting your FC targets? The way you worded it in the first posts makes it sound like you're shooting from the hip a bit...can you post a full set of test results from your TF-100 or K-2006 test kit -
FC
CC
pH
TA
CYA
It turned blue this afternoon after I dosed it with bleach again. Hopefully I'm on the right track now. The filter and sand is only a year old but I took the valve off last week and I've lost about an inch or so of sand (I marked where full was on the outside with 700 lbs of sand.) I don't think that's enough to cause an issue but I might put another bag or two in it. I'm not sure why you think I'm shooting from the hip but those numbers you requested are in the first post. I'm trying to maintain 12 ppm FC.
I see the numbers now. They are hard to see inline! The next time you test, if you could please put them like this:
FC
CC
pH
TA
CH
CYA
we'll be able to see them and wrap our brains around them. No problem!
FC
CC
pH
TA
CH
CYA
we'll be able to see them and wrap our brains around them. No problem!
Ha! I was just coming to ask my idle question about why I never get CC even when I have a mess to clean up. Just went through a short slam as I let the water temp get too high about a week ago and wasn't paying attention to clorine levels (now that is is all clean and sparkly it is cool and windy again. sigh) The first night I had a 10 ppm loss from shock level, but as usual never got a CC reading. not too many bathers but plenty of natural dirt and then algae are my problems. NOW it makes sense, thanks!