Chlorine levels go down close to zero overnight.

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M

mcanturdz

Member
Dec 14, 2020
10
Florida
Pool Size
10000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Truclear / Ei
Hello! These are the test results from my most recent visit to the pool supply store 5 days ago. The water sample was from the morning, pump and chlorinator hadn't run since 6PM the day before:

TC 0.5 PPM
FC 0.5 PPM
CC 0.00 PPM
pH 7.8
Total Alkalinity 90 PPM
Calcium Hardness 500 PPM
Stabilizer 70 PPM
Total Dissolved Solids 4300
Salt 3000PPM

I brushed the entire surface, cleaned the filter, cleaned the salt chlorinator; and I added 2 cups of Acid. I let the system run for 1 hr and then I added 2 capfuls of Pool Perfect + Phosfree in the skimmer.

And these are the results from my test today, the pump and chlorinator have been running for 9hrs (since 10AM):
Total Hardness 600 PPM
TC 3 PPM
FC 1 PPM
pH 7.4
Total Alkalinity 40 PPM
CYA 30 PPM
Phosphates ~300 ppb

I'm using AquaCheck test strips, so it's hard to read the results. After reading through TFP posts, I decided to order Taylor K-2006C test kit. So I should have more reliable readings soon.

In the last 6 months or so, I've been having issues with phosphates. Chlorine level goes down, all other levels are fine but phosphates are high. I've used at least 3 different types of phosphates removers. Salinity and Suncoast didn't work (levels went down little to nothing). Suncoast Super and NC Phosfree seemed to work. Current phosphate levels are at 300 ppb and if I'm correct this is an acceptable level.

The water looks crystal clear. But, the chlorine levels are normal at the end of the day (after the chlorinator has been running for ~9hrs at 70%) and they are very low in the morning.

Should I keep trying to lower the phosphate levels? What I'm I missing?

Thank you in advance for your answers/comments!

Martin C.
Central Florida East Coast
11K gal, Quartz resurface July-2019, 1 HP variable speed Jandy VSFLOPRO pump, Jandy 150 CS FILTER, Jandy TRUCLEAR salt chlorinator, Sunblazer heater, Zodiac MX6 cleaning robot.
 
Hope you get this squared away. I am in central fla...muriatic acid after rain to lower my PH and liquid chlorine are the only 2 chemicals we use. Pool water xtal clear. LC usage a little over a gallon/week as it gets hotter. My CYA close to 100 (prior maintainer used tabs)so i keep FC between 7 and 11ppm.
 
YippeeSkippy said:
Do you have your own TFP endorsed test kit? We can't comment on pool store results as they're often way off base wrong.

What size salt cell do you have? Is it sized for at least 2X your pool's volume?

Do you ever augment your FC with liquid chlorine?

FC/CYA Levels

Recommended Levels
Click to expand...
I just ordered TF-100 test kit today. I'll report back once I have the test results.

My pool is 11,000 gallons. I have a Jandy TruClear Saltwater Chlorinator. Not sure about the "size", but the brochure says: "produces 18 grams of chlorine for pools up to 35,000 gallons.". I have it at 70% running for 8.5 hrs a day. Chlorine levels do get higher by the end of the day but go back down the next morning. I've had it for 2 years. For the first ~16 months, running it at 30% for 6-7 hrs/day was more than enough. Could it be a chlorinator issue?

I never use liquid chlorine. I used a "1lb bag of Salinity Surge Shock" from Pincha Penny a few months ago, I think it was after the 2nd time they tested high levels of phosphates. Should I add liquid chlorine? What type or brand is better for this?

Thank you!
 
Last edited:
jeremycrook said:
We have a pool about the same size, double check the CYA (cyanuric acid). Mine was a low and it was hard to keep my chlorine levels up in the desired range.
Click to expand...
My test kit arrives on Monday. I don't have a reliable way of testing CYA right now. Pool supply store said 70 for the stabilizer but I see 30 (maybe less) with the hard-to-read test strips.

Testing with my cheap drop test kit in the afternoon, after the SWG has been running for 9 hrs at 70%, I get FC 1.5 and CC 1.5. The following morning I get FC 0.5 and CC 0.5.

I think I need to shock with liquid chlorine. Right?
 
mcanturdz said:
I think I need to shock with liquid chlorine. Right?
Click to expand...
While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
 
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mcanturdz said:
My test kit arrives on Monday. I don't have a reliable way of testing CYA right now. Pool supply store said 70 for the stabilizer but I see 30 (maybe less) with the hard-to-read test strips.

Testing with my cheap drop test kit in the afternoon, after the SWG has been running for 9 hrs at 70%, I get FC 1.5 and CC 1.5. The following morning I get FC 0.5 and CC 0.5.

I think I need to shock with liquid chlorine. Right?
Click to expand...
Listen to @mknauss he's a pro, I'm just an end user. But I'd make sure of the CYA level, and second I'd get to the CC. Grab a big pack of bleach for the time being, and go through the steps to narrow down your issue. Something isn't balanced or there is some sort of issue, generally speaking the pools are pretty easy if you follow the process.
 
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mknauss said:
While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
Click to expand...
I added 70oz of liquid chlorine last night. Cheap test showed both FC and CC at ~4.0. This morning they are both still at ~4.0.

Just wondering, could there be a problem with the SWG? It’s a Jandy Truclear 11k, 2 years old.

Thank you!
 
We can't speculate where the problem lies until we get test results from your new kit. Those test results will guide the questions we ask to troubleshoot your problem. Your kit should be there in a couple of days, so stick with adding liquid chlorine daily for now.
 
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I received my test kits and here are my results:

Salt 4,000 ppm
FC 3.0
CC 0.5
CH 875
PH 7.8
TA 80
CYA 30

I added 70oz of liquid chlorine Friday night, 70oz Saturday night, and 35oz Sunday night (last night).
Didn't run the SWG on Saturday, ran it at 30% for 7hrs on Sunday. Today, it's been running at 30% for 5hrs.

Calcium Hardness seems high and CYA seems low.

I will retest everything tomorrow morning and share the results.

Thank you!
 
I would raise your target FC level for a while. If your CYA is really 30, it won't hurt to run at FC of 5 or 6 and see if chlorine levels hold better at night. With a salt water chlorine generator, your CYA should really be higher though...in the 70-80 range. This will help to buffer against FC loss to the sun.
 
I received my TF-100 test kit Monday night.

Tue-4PM
Salt 4,000 ppm
FC 3.0, CC 0.5, CH 875
PH 7.8
TA 80
CYA 30
Added 3lbs of Pool Mate Stabilizer
Ran pump and SWG at 50% for 24 hrs.

Wed-6PM
Added 70oz of liquid chlorine

Wed-8PM
FC 8.5, CC 0.5

Thu-8AM
FC 6.5, CC 0.5
Lowered SWG to 30%
Ran pump and SWG for 8hrs

Fri-9PM
After running pump and SWG at 30% for 8hrs
FC 2.5, CC 0.5

It's been cloudy all week, with heavy rains on Wednesday.

I can't figure out why is chlorine still going down?

I'll do a complete test (including CYA) tomorrow morning.
 
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