Chlorine, Ammonia, and bather load

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J

Julia'sPool

0
Jun 19, 2015
26
Northampton PA
First a confession...I cheated on my SLAM.

Started SLAMming and pool was just eating chlorine. I ran out of one of the chemicals to test the chlorine. I had to order it online, as no one carried it.

(Side note: Leslie's Pools will never get another penny from me for anything! Sent me on a wild goose chase to 3 different stores, each one saying, on the phone, that they had it, but when I showed up, they tried to sell me the wrong thing. One clerk argued with me that I was wrong and the testing chemical I was asking for was NOT for chlorine, until I showed it to her on Leslie's web site).

So while I waited, I continued to add the same amount of Chlorine that I was previously. Test chemical arrived and I passed all the tests (water not crystal clear, but very close). And I passed the overnight test.

Pool was still consuming chlorine like crazy, so I tested for ammonia and came up with less than .25 ppm. But Chlorine seemed to stabilize (and no CC, so I thought the ammonia was not a problem).

I usually test my pool everyday there are swimmers, and every other day if no one swims. Except Tuesdays. On Tuesdays I am out of the house from 4 am until 10 pm. So Wednesday morning I tested and Chlorine was 0 and Combined Chlorine was 0. I quick added chlorine before I left. Came home to 6 kids in the pool and found out there were about 10 the day before.

Tested again and found only 1ppm of Chlorine and no combined chlorine. This had me confused. I added more chlorine and after an hour I did a full test.

FC 4.5
CC 0
PH 7.5
TA 90
CYA between 30 and 40
CH 80
Ammonia .5 ppm

Now I think the bather load was too high for my little pool and this caused the ammonia to go up and the chlorine to go down. Does this seem right?

I will do an over night test and post the results tomorrow morning.

Do I need to address the ammonia problem? Or was it just too many people using the pool?

Sorry for the long ramble.

Julia
 
I can't directly address whether the ammonia is a problem - cause I don't really know. Someone more knowledgeable should be along shortly.

You may wish to do an OCLT to see exactly how much FC you lose overnight.
BTW - "water not crystal clear, but very close" isn't quite good enough to completely pass the SLAM criteria.

Would also probably be a good idea to make all those kids take mandatory potty breaks too. If they adding bodily fluids to the water, it certainly isn't helping the issue.
 
Teens and twenty somethings ARE just kids - with higher bodily fluid volumes (anyone < 35 is just a kid to me). It's "easier" for them not to get out of the pool. :drown:

Of course, 10 people in 5,000 gallons (for who knows how many hours) is quite a high bather load. You may wish to consider upping your target FC a few points. That might help keep you above minimum for the day.
 
Just dropping in with I agree, keep the FC up, if it continues dropping when no one has been swimming look for places with poor circulation where algae may be hiding (under steps, light niches, those sorts of things)
 
Results of OCLT were as follows:

FC 3.5
CC 0

Where is the chlorine going? Should I do a SLAM? Is there some type of formula for bather load, that is "math-easy"?

Talked to kids and hubby about number of people in the pool...pointless...hubby is retired and loves playing host.


2016061.jpg
 
Julia'sPool said:
Results of OCLT were as follows:

FC 3.5
CC 0

Where is the chlorine going? Should I do a SLAM? Is there some type of formula for bather load, that is "math-easy"?

Talked to kids and hubby about number of people in the pool...pointless...hubby is retired and loves playing host.
Click to expand...
Is that FC 3.5 your level at the start of the OCLT or the end of the OCLT?

Are you following the OCLT procedure exactly as written?

"To perform the overnight FC loss test:
  1. If you have an SWG, tablet chlorinator, or other chlorine feeder, shut it off completely.
  2. After the sun goes down, and at least 30 minutes after your last chemical addition of the day, test your water for FC using the FAS-DPD test making sure your FC level is at least above 3ppm.
  3. Record that result. Do not put any more chlorine in your pool.
  4. The next morning, as early as practical and definitely before there is any direct sunlight on the pool, perform the FAS-DPD FC test again and record the results."

With the bather load (chlorine demand) you have, your FC level is too low. The recommended FC target for the 'average' pool at 40ppm CYA is 5ppm, with the minimum at 3ppm (http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock). Both FC levels you posted are below the recommended target. My pool is partially under two large trees that constantly drop organic matter into the pool, thus requiring me to keep my FC 1-2ppm above the recommended target or my water will begin to turn cloudy (algae bloom starting) when the water temp gets into the mid 80's & we are using the pool everyday.

If you did the OCLT properly, and have lost 1ppm or more overnight, you will need to properly SLAM the pool. NO SHORTCUTS. As you are discovering, shortcutting the SLAM procedure will turn the SLAM into a waste of your time & money, leaving you with an unsanitary pool.

Dom
 
Sorry.

OCLT results:
Evening:
FC 4.5
CC 0

Morning:
FC 3.5
CC 0

So I lost about 1 ppm of FC overnight.


The bather load was extreme and unusual...both kids agreed to have friends on the same days...usually if one has friends over, the other refuses to use pool. They can't agree on the time of day.

I am still wrapping my head around how chlorine works. I don't understand how I can lose free chlorine and have no combined chlorine.

I might just do a slam anyway, just to be sure.

Results before OCLT

FC 4.5
CC 0
PH 7.5
TA 90
CYA between 30 and 40
CH 80
Ammonia .5 ppm

The picture in my above post...is that water considered to be "clear"? You can see the pattern of the pool liner and tell that my kids forgot to vacuum last night. But it isn't that sparkly-crystal clear I had last year.




 
It's better to do an OCLT at about 10 FC or higher.

If all of the work the chlorine is doing is during the day (bather load) the CC can be burned off by the sun as they are generated. If there are organics in the water that the FC works on overnight, there might be CC, or if there is a LOT of stuff for the chlorine to work on and the sun can't "keep up" and burn off the CC it will show as well.

It would not hurt to bring FC up to SLAM levels, but I suspect you don't have much of a problem. Just teenagers :)
 
Raising the FC will get rid of the ammonia. When you have ammonia it raises the FC demand. You may or may not have CC show up on a test because it is constantly created by oxidizing contaminates in the water, and constantly being broken down by the sun and additional chlorine. When you have small amounts of CC it may or may not be present at the time you pull the sample for testing.

The water is a little dull, so after everyone is done with the pool for the day, raise the FC to slam level, top off the FC after the sun goes down, and check it again in the morning. Train the teens to test the chlorine and bump it back up when they are done swimming and it won't matter how many kids they have in the pool.
 

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