Large Daily Chlorine Loss

jbrzezinski

Member
Jul 10, 2019
9
Georgia
Hi guys, I’m a pool newb and I’ve been converting my pool to TFP levels over the last couple of weeks. When I received my k2006 kit I found that my chlorine was low, like 1.5ppm, but CYA was unmeasurably low as well. I brought up my CYA over the next several days and my chlorine levels with it according to the CYA chart.

By my testing, it seems as though I’m losing something like 4ppm of chlorine per day. For my SWG, which is sort of oversized, to put out that much it needs to run something like 14 hours at 100%.

Question: is this a normal daily loss of chlorine? Seems like I’m going to torch my SWG trying to keep up with the high chlorine levels needed at higher CYA levels.

Test results 24 hours ago:
FC: 2.5 CC: 0
PH: 7.3
TA: 70
CH: 350
CYA: 80
I added 32 oz of 12.5% chlorine and ran SWG for 9hrs at 70%

Test results tonight:
FC: 2.0
PH: 7.0

I added enough liquid chlorine tonight to get it to 6ppm, and then adjusted the SWG to 100% for 9hrs between now and tomorrow same time.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome! :wave: Sounds like you've already got the algae bug. Best thing to do right now...... perform an Overnight Chlorine Loss Test. Make sure to turn off the SWG and take one final FC reading after the sun sets, then test again tomorrow morning before the sun hits the water. If you lose more than 1ppm of chlorine overnight, it's time for the SLAM Process.
 

jbrzezinski

Member
Jul 10, 2019
9
Georgia
Welcome! :wave: Sounds like you've already got the algae bug. Best thing to do right now...... perform an Overnight Chlorine Loss Test. Make sure to turn off the SWG and take one final FC reading after the sun sets, then test again tomorrow morning before the sun hits the water. If you lose more than 1ppm of chlorine overnight, it's time for the SLAM Process.
Thanks for the reply...even with CC of 0 and water is crystal clear? I’ll do overnight test tomorrow night.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
11,382
Evans, Georgia
Here in Augusta it was 100 degrees yesterday with full blazing sun. yeah.... I can easily imagine a 4ppm FC loss yesterday.
Alternatively, how old is your cell, and does it need cleaning?
Maddie :flower:
 

Grnctrtl

Active member
Sep 6, 2018
27
Haslet/Rhome, Texas
I have had had to do a SLAM with what I thought was crystal clear water and 0 cc because I had an algae bloom that I was barely keeping at bay. Never saw anything green, but the water got extra clear after a 4 day SLAM.
 

jbrzezinski

Member
Jul 10, 2019
9
Georgia
I have had had to do a SLAM with what I thought was crystal clear water and 0 cc because I had an algae bloom that I was barely keeping at bay. Never saw anything green, but the water got extra clear after a 4 day SLAM.
I could see that being the case as it was clearly under-chlorinated before I got my test kit.

I tested this morning and FC is 7.5, and SWG should add 1.7 more later this morning. I’m going to assume that 9.2 max was in the water when I test this evening before I do the OCLT. Then I’ll know exactly what I lost during the day and then overnight.

Pool party is on Saturday so fingers crossed...
 
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YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
11,382
Evans, Georgia
When ever my pool needs a bit of a chlorine boost, even though I have a SWG, I just use liquid chlorine. Its fast, cheap and assures me that all will be well in my pool world. Remember that SWGs work slowly, and sometimes I want instant gratification! :mrgreen:

If you've got doubts and that party coming up, keep some at hand for extra FC when you need it. Like right before and right after group swim parties! :)

Maddie :flower:
 

IceShadow

Gold Supporter
Jun 8, 2019
1,070
Milwaukee, WI
I would recommend turning off the SWG then doing a FC test after sunset. Don't run with math - you never know what might have happened. Better to do an actual test tonight and then one in the morning to see if you have anything eating your FC up at night. :)
 

jbrzezinski

Member
Jul 10, 2019
9
Georgia
Results tonight:
FC: 3.4
CC: 0
PH: 7.4
TA: 75
CYA: 80

My question is, with FC being low like that, am I putting my pool at risk by not adding any tonight while I do the OCLT?

Also, if I do need to start a SLAM tomorrow, is it ok to swim while I SLAM?
 

jbrzezinski

Member
Jul 10, 2019
9
Georgia
Results tonight:
FC: 3.4
CC: 0
PH: 7.4
TA: 75
CYA: 80

My question is, with FC being low like that, am I putting my pool at risk by not adding any tonight while I do the OCLT?

Also, if I do need to start a SLAM tomorrow, is it ok to swim while I SLAM?
One more question, for the results of the OCLT to be valid, do I need to measure the first time when it’s dark or just when the sun is no longer on the water?
 

Grnctrtl

Active member
Sep 6, 2018
27
Haslet/Rhome, Texas
You can add the amount you need to get to the level you want and do another test after the addition so you don’t risk it. Maybe wait 30 minutes and see where you are after the chlorine addition.

ETA: for your SWG pool with a CYA of 80 you minimum CL level is 4 per the chart.
 
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jbrzezinski

Member
Jul 10, 2019
9
Georgia
Passed the OCLT, FC was 3.0 this morning for a loss of approx .4ppm. I added enough chlorine to get it to 6 and cranked up the SWG again.

So I guess the next step is to figure out if I really am losing that much FC every day or is the SWG not putting out what it should? Again, pool is 2 months old.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Passing the OCLT is great, but you seem to have been riding the very low end of the FC scale for your CYA. As Austin Powers would say .... "Living dangerously". :) According to the FC/CYA Chart and your CYA of 80, your FC should never have been below 4 ppm. In this heat that's an invitation to alage. That may be why your water is struggling. Getting back to the target of 6 this morning is good, but you might even keep that bleach handy and give it a couple extra shots today, this evening, and tomorrw morning. It wouldn't hurt anything to pump your FC to 8-10 in preparation for your weekend. If things stabilize - great. Make sure to never let the FC drop below 4. If it does drop again, either your SWG is not performing well or you'll want to do another OCLT. Next time you do the OCLT, get the FC up to about 6 or so at the start. Good luck!
 

jbrzezinski

Member
Jul 10, 2019
9
Georgia
Update: pool party went great, and by the time everyone was done swimming and pool was in shade, FC was still hanging out around 6. Not bad! From there I’ve been able to keep it in the higher end of the recommended range, and today it was very stable staying around 8 all day.

Two things I changed: first was to keep the FC on the high side of the recommended range rather than shoot for the middle. Second, I changed my pump schedule to only run during the day while sun is directly on the pool rather than break it up with half during the day and half at night. It seems to have helped for whatever reason?

Anyways thanks for the help guys! Pool looks awesome.