Won't hold chlorine

hawkmoon7

Well-known member
Nov 27, 2020
56
Florida
Hey everyone, I was wondering if anyone had any thoughts about why my pool is eating chlorine:

I have a fairly new pool, that's mostly shaded (3 month old Pebble-tech pool with SWG). The builder monitored the chemicals for the first 2 months. Everything was in the perfect range the whole time, but chlorine was a bit high every time I tested it (4 to 4.5 ppm) so I kept reducing the output of the SWG (eventually it was reduced to 20%). When the company stopped servicing the pool, chlorine dropped to 0. I found out later that every week, they'd add a gallon of liquid chlorine because it was low. I would test the pool myself later that day and find it high, and I thusly lowered the SWG. The cycle continued this way until they stopped coming and I started taking samples in to Pinch-a-Penny).

Since then, everything checks out. They even did a phosphate check and found nothing. However, the SWG is on 100%, 10 hours a day. The pool tests at 0 PPM. Pool company was called and they tested the SWG. They say it's working fine. Samples directly from the returns show chlorine (@ about 1PPM).

I added 1.5 gallons of liquid chlorine last Friday. Tested 4 ppm after a few hours. The next day, 1ppm. I added another half gallon and it jumped to ppm. The next day, 0. Water has always looked clear and perfect. But it is eating chlorine. How is this possible?

Total and free Chlorine: 0ppm
PH: 7.6
Alkalinity: 90PPM
Calcium: 350ppm
Stabilizer: 60ppm
salt: 3500ppm
 
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hawkmoon7

Well-known member
Nov 27, 2020
56
Florida
I should add that for the last 3 weeks, the test report has come back the same each week (all chemicals are fine but chlorine is 0 ppm). In response, I have been adding a gallon of liquid chlorine every week afterward and gradually raised the SWG from 20% to now 100%). SWG does make tiny bubbles from time-to-time out of the returns and it will also leave calcium flakes in the pool under each return when the water isn't disturbed too much. I checked the SWG and the plates are clean.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,565
NY
Hey Hawk !!! Run another CYA test. Use the same sample and run it a few times to make sure you are happy with 60. If it’s 60 it’s a bit low for FL. You’ll want 70 for now and probably 80 when your sun/UV goes nuclear in the peak season.
 

hawkmoon7

Well-known member
Nov 27, 2020
56
Florida
Thank you. Showing around 60 on my test strip (I have two different brands, both around the same). Also shows 60 in all of the last few weeks of Pinch-a-Penny. I'll go higher on the stabilizer. I can do right now actually as I have some left over. I'll aim for 80.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,565
NY
ABORT mission !!!!!! Test strips are terrible. It could very well be 40 and *really* explain the drops. But if you can’t really say what it is, you cant add accordingly and might overshoot needing to drain.

You need a TF-100 pro from TFtestkits.net and pronto. Specifically for this now, but also in general. It will keep you in the know and trouble free.

Keep up with the FC dosing until the kit comes and we will go from there once you have reliable results.
 

anre5180

Member
Oct 1, 2020
15
Miami, FL
Hey everyone, I was wondering if anyone had any thoughts about why my pool is eating chlorine:

I have a fairly new pool, that's mostly shaded (3 month old Pebble-tech pool with SWG). The builder monitored the chemicals for the first 2 months. Everything was in the perfect range the whole time, but chlorine was a bit high every time I tested it (4 to 4.5 ppm) so I kept reducing the output of the SWG (eventually it was reduced to 20%). When the company stopped servicing the pool, chlorine dropped to 0. I found out later that every week, they'd add a gallon of liquid chlorine because it was low. I would test the pool myself later that day and find it high, and I thusly lowered the SWG. The cycle continued this way until they stopped coming and I started taking samples in to Pinch-a-Penny).

Since then, everything checks out. They even did a phosphate check and found nothing. However, the SWG is on 100%, 10 hours a day. The pool tests at 0 PPM. Pool company was called and they tested the SWG. They say it's working fine. Samples directly from the returns show chlorine (@ about 1PPM).

I added 1.5 gallons of liquid chlorine last Friday. Tested 4 ppm after a few hours. The next day, 1ppm. I added another half gallon and it jumped to ppm. The next day, 0. Water has always looked clear and perfect. But it is eating chlorine. How is this possible?

Total and free Chlorine: 0ppm
PH: 7.6
Alkalinity: 90PPM
Calcium: 350ppm
Stabilizer: 60ppm
salt: 3500ppm
any update on this?

I am having similar behavior with my SWG... originally installed 8 months ago. already has been replaced 1 month ago thru warranty.

 
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hawkmoon7

Well-known member
Nov 27, 2020
56
Florida
any update on this?

I am having similar behavior with my SWG... originally installed 8 months ago. already has been replaced 1 month ago thru warranty.

Yes... I had to get the TFP testing kit and follow the TFP protocol for SLAMing the pool. Took about 6 days. After the SLAM, the water turned a crystal quality it had never reached before. Something was living in there. It turned out I had a form of "clear algae". When I added the liquid chlorine, the TFP testing kit confirmed that none of it was free chlorine for long... it all became combined and then vanished. Before the SLAM I was at 100% on the SWCG for 12 hours a day with no detectable chlorine levels. After the SLAM, I keep it at 55% for 10 hours a day and the chlorine has held at 5ppm even in constant summer sun.

The 3 days took around 4 gallons of bleach a day. Then it dropped to 1 and then 1/2 for days 5 and 6. It seemed like way too much chlorine for a pool that looked pretty clear. But it solved the issue.
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,855
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
full
 

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