Never Ending Chlorine Demand ?

[Diverdown]

I come to the forums seeking the sage advice and wisdom of the pool gurus

I had an issue last year with my pool eating stabilizer and shock (I shocked with Bioguard Burnout 35 and Burnout Extreme) and I now realize that I closed at the end of the season without resolving the issue.

I opened this year to continue the pool saga and opened to a cloudy pool and I have spend easily over $250 trying to eliminate the chlorine demand issue without having it resolved (I opened April 2nd).

I have been going back every couple of days to the pool store and it was beginning to cost a fortune with no end in sight.

My last details (this morning) are as follows:

Salt Pool - 68,000 liters (18,000 gallons approx)
Salt Water Pool
Vinyl Finish
Temp - 60 deg F (16 deg C)

Test Results via Bioguard ALEX program (I just ordered today the Borate Test Strips (Boric acid to be added tomorrow), SpeedStir Magnetic Stirrer and a Test Kit so I need to rely on testing from the local pool supplier until they come in).

CYA - 30
TC - 1.5
FC - 0
PH - 7.5
TA - 155
CH - 215
Mineral Level - 3400

I have shocked over several days (not hours as per the protocol) with the following (I realize that it was not done correctly and I was just throwing away money).

2 bags burnout extreme
4 bags burnout extreme
4 bags burnout extreme
10 liters (2.6 gal) of Florchem-19 Sodium Hypochlorite (liquid chlorine - I believe it is 12% but they did not know at the pool store)
20 liters (5.2 gal) of Florchem-19 Sodium Hypochlorite (liquid chlorine - I believe it is 12% but they did not know at the pool store)

After I did my pool test this morning I shocked with:
60 liters (15.85 gal) of Florchem-19 Sodium Hypochlorite (liquid chlorine - I believe it is 12% but they did not know at the pool store)

I slowly poured 20 liters (5 gal) of the chlorine, scrubbed the bottom and sides, poured an additional 20 liters (5 gal) and scrubbed the bottom and sides and did the same for the remaining chlorine. Pump floor drain only open and pump running on high with solar cover on after application was complete.

I will go to the pool store to get a water test after 1 hour for a baseline and again after 3 hours to see if the chlorine demand issue is resolved.

In frustration last year I discovered that I had very high phosphates and I used phosfloc and vacuumed to waste and the chlorine demand was eliminated earlier in the season and I could turn my salt generator down from 55% to 20% and maintain perfect chlorine levels.

I used phosfree this season (got it by mistake, I thought it was a floc) and I did not to vacuum to waste as per the instructions and the pool cleared right up but the chlorine demand remained (pool is still cold).

In using the calculator I only needed a very small amount of shock (1.7 liters or 56 oz).

Am I using the calculator wrong?

I have been shocking with substantially more and nothing has happened to the chlorine demand so I may have gone overboard with the 60 liters (15.85 gal) of 12% chlorine, but even using the 20 liter (5.2 gal) did nothing to resolve the chlorine demand and free chlorine was still 0 after the previous applications.

I have moved to the BBB method since I discovered the forums

Any tips, advice or insight would be very much appreciated.

Thank you in advance

 

[JohnT]

Welcome to TFP.

Your CYA(Stabilizer) level is awfully low for a SWCG pool. 70 or 80ppm is typical. What model do you have? IN your cold water, it's possible that your SWCG is not even producing chlorine. Do you know how old the cell is or if it has been cleaned recently?

You are putting an awful lot of chlorine in at once for a vinyl pool. 5 gallons of 12% in 18,000 gallons of water would raise your chlorine by 35ppm, which is well beyond what most test kits can test. Only the DPD-FAS test can measure that high, so any results you got from another test are unreliable.

 

[Bama Rambler]

WOW! I'll let the real experts jump in here but adding 60L of 12% to a 60,000L would have raised your FC by 120ppm. My recommendation is to stop adding anything till the levels come down and you can test properly. There's no consumer kit that I know of that'll even come close to testing chlorine that high.

 

[Diverdown]

I have the Goldline Aquarite TCell 15 salt generator and it is 4 seasons old.

The SWCG indicates that it is producing chlorine and it was cleaned at the end of the pool season and I checked the operating input / output voltages now and it is working perfectly.

I turned off the SWCG before adding the chlorine and I also just removed the pool solar cover.

I just received the water test results and as you indicated they were off the scale.

I will be checking again in a couple of hours.

 

[Diverdown]

WOW! I'll let the real experts jump in here but adding 60L of 12% to a 60,000L would have raised your FC by 120ppm. My recommendation is to stop adding anything till the levels come down and you can test properly. There's no consumer kit that I know of that'll even come close to testing chlorine that high.

I am sure that you are right that I probably went overboard, but 20L did absolutely nothing and I was at 0 free chlorine the next day.

I must have a chlorine monster in the pool

 

[frustratedpoolmom]

It's difficult at this point - cuz you are kinda guessing. We can't really poinpoint the problem without your own FAS-DPD test to test with. For instance - we can't pinpoint if the liquid chlorine is the problem because we don't know if you are actually reaching your target or if something is still consuming it. We can't pinpoint if the CYA reading is to blame - see below.

Is that the only brand of liquid chlorine available to you? The water is clear now, but you just can't get the FC to hold?

We like to see FC and CC - what is "sanitizer" in their terminology?
("Free" must be FC, right?)

The ALEX system is a strip reading testing system. Even though it's computerized its basically flawed because it uses strips and purportedly the system is designed simply to sell chems. I don't trust that CYA reading.

In using the calculator I only needed a very small amount of shock (1.7 liters or 56 oz).

What values did you put in the "now" and what did you enter for the "target"?

 

[JohnT]

WOW! I'll let the real experts jump in here but adding 60L of 12% to a 60,000L would have raised your FC by 120ppm. My recommendation is to stop adding anything till the levels come down and you can test properly. There's no consumer kit that I know of that'll even come close to testing chlorine that high.

I am sure that you are right that I probably went overboard, but 20L did absolutely nothing and I was at 0 free chlorine the next day.

I must have a chlorine monster in the pool

It COULD be that you have so much chlorine that the strips are bleaching out and measuring 0ppm.

 

[Bama Rambler]

It COULD be that you have so much chlorine that the strips are bleaching out and measuring 0ppm.

That's my bet. Adding the 2 bags of burnout extreme raised the FC level by 24 ppm which was effectively over anything the pool store could read so they listed it as zero. IMO

 

[frustratedpoolmom]

2 bags of burnout extreme - it's Cal-Hypo 47% isn't it? If each bag is 16 oz I calculated about 6.3 on the FC ...

 

[bk406]

Yep, 47%.

 

[Diverdown]

It's difficult at this point - cuz you are kinda guessing. We can't really poinpoint the problem without your own FAS-DPD test to test with. For instance - we can't pinpoint if the liquid chlorine is the problem because we don't know if you are actually reaching your target or if something is still consuming it. We can't pinpoint if the CYA reading is to blame - see below.

Is that the only brand of liquid chlorine available to you? The water is clear now, but you just can't get the FC to hold?

We like to see FC and CC - what is "sanitizer" in their terminology?
("Free" must be FC, right?)

The ALEX system is a strip reading testing system. Even though it's computerized its basically flawed because it uses strips and purportedly the system is designed simply to sell chems. I don't trust that CYA reading.

In using the calculator I only needed a very small amount of shock (1.7 liters or 56 oz).

What values did you put in the "now" and what did you enter for the "target"?

I can get chlorine from elsewhere if needed. The pool place has a massive vat (equivalent to many drums of chlorine) in the back and they have only been open since last season so the chlorine was there for no more than a year.

The water is clear after I used the phosfree but the FC won't hold.

Sanitizer is chlorine in their test report.

I put in one pail of CYA a couple of weeks ago, and it should be up to 30 as per the instruction on the bottle. There was no CYA visible during previous tests.

For the calculator I put in now as 0 and target at 3 at 12% bleach for 68,137L (18,000 gal).

The ALEX system they use is a computer program where they input the results after they generate the tests manually. It is not a strip based system and operator error in conducting the tests manually is possible.

 

[Diverdown]

It COULD be that you have so much chlorine that the strips are bleaching out and measuring 0ppm.

That's my bet. Adding the 2 bags of burnout extreme raised the FC level by 24 ppm which was effectively over anything the pool store could read so they listed it as zero. IMO

The FC and TC is not a strip based test. It is a manual test using the standard drops in vial (it may be a pill in foil, I will check when I go back in an hour) that is then visually compared against a reference color strip with a back light.

The results are manually input into a computer program that generates the report.

 

[Diverdown]

2 bags of burnout extreme - it's Cal-Hypo 47% isn't it? If each bag is 16 oz I calculated about 6.3 on the FC ...

That sounds right, but the reading from the printout I have in front of me says 5 bags of Bioguard Burn-out 35 or 4 bags of Burn-out extreme.

I had done the burnout route a few times previously this season and it had not resolved my FC issue, so I went with liquid chlorine (cheaper as well).

I think the whole Bioguard thing is a huge cash grab and look forward to cleaner, better water with the BBB system at a fraction of the cost

 

[frustratedpoolmom]

OK good. You sure they didn't use strips? I thought the ALEX just read strips.

Do you by any chance have a cheap OTO chlorine test - the yellow, drop-based kind? Often pool stores sell these 2-way kits for chlorine and PH.

If you tested with that - if its a "bleach-out" situation - the color would be very dark orangy brown. If it's clear or barely yellow then we can confirm if it's too much or too little in this situation.

Not sure how long it will take for your kit to arrive but if you don't have one you might want to pick up one of those small kits for today, shouldn't be too much $$, just for reassurance. IF you confirm it's "too little" chlorine I'd make your Target 10 - since you know you have CYA in there - because you added it, then 3 is not high enough perhaps there is still some sort of FC demand causing it to drop like a rock.

But I wouldnt add any more chlorine until you can confirm what's happening - bleaching out or too little.

Hope that helps/makes sense and that I didn't confuse the situation

 

[Diverdown]

OK good. You sure they didn't use strips? I thought the ALEX just read strips.

Do you by any chance have a cheap OTO chlorine test - the yellow, drop-based kind? Often pool stores sell these 2-way kits for chlorine and PH.

If you tested with that - if its a "bleach-out" situation - the color would be very dark orangy brown. If it's clear or barely yellow then we can confirm if it's too much or too little in this situation.

Not sure how long it will take for your kit to arrive but if you don't have one you might want to pick up one of those small kits for today, shouldn't be too much $$, just for reassurance. IF you confirm it's "too little" chlorine I'd make your Target 10 - since you know you have CYA in there - because you added it, then 3 is not high enough perhaps there is still some sort of FC demand causing it to drop like a rock.

But I wouldnt add any more chlorine until you can confirm what's happening - bleaching out or too little.

Hope that helps/makes sense and that I didn't confuse the situation

I am 100% sure they did not use test strips. Another pool place uses the ALEX program with the strips, but this place uses the manual testing with visual inspection against a lighted background with color reference for all of their testing. There is a name for the testing center that is used, I will get it when I go back in an hour.

I won't get my kit until next week. I did test with a Walmart test kit and the color is at the highest end now. Previous to the addition to the chlorine it was minimal. When I went in for my reference test an hour after chlorine application, both the FC and TC vials were at the highest end (I think their test could only go up to 8).

I definitely won't be adding any more chlorine. My intent was to literally "shock" the pool as the previous 20L did not have any effect on FC.

I have taken the cover off of the pool, turned on the stair jets and waterfall (stone 3 tier drop 5' waterfall cascading into the pool) to reduce the chlorine level. It is nice and sunny so hopefully there will be a reduction in chlorine so that the test can provide more valid results.

I have also taken a water sample from the pool into the house to warm up gradually prior to the test. I am wondering if the cold water is affecting the stabilizer reading and I will provide the warm sample to the pool company to conduct a repeat stabilizer test. Also does stabilizer remain in the pool from the previous season?

I will take a second water sample at pool temp in an hour so it can be tested after the effects of sun and aeration from the waterfall and stair jets have taken effect and let you know the results from the test when I return.

Thank you for your help and advice.

 

[frustratedpoolmom]

So the walmart kit is showing Yellow? how dark is the shade of yellow? yellow... orange yellow, orange brown?

Yes, cold water can affect the CYA test. Are you testing with the Wal-mart kit? You can actually warm it up with hot water in a cup, swirling the mixing tube in the hot water to bring up the temperature of the sample.

Yes, CYA remains from the prior season. In some pools it can disappear over winter but that doesn't always happen and we really don't know why it does only some of the time.

Does your tap water have chlorine? You can try the shot glass method with your OTO test.

Take 3 parts chlorine-free water and 1 part pool water. Mix it together and then use that as your sample for the OTO test. Then multiply the results by 4. This will allow you to read the TC up to 20 but it does lose some accuracy.

 

[JasonLion]

The DPD chlorine test, which measures FC and TC as shades of red compared to a color standard, will bleach out to clear and show an FC level of zero when the FC level is too high. Depending on various things it can start bleaching out at FC levels as low as 10, and it will definitely be bleached out by the time FC reaches 20. Dilution can extend that range a bit with a corresponding loss of precision.

The OTO chlorine test, which measures TC as shades of yellow compared to a color standard is much more reliable about changing color when there is chlorine present. If there is chlorine it will turn some shade in the yellow/orange/red/brown family and if there isn't any chlorine it will remain clear.

 

[frustratedpoolmom]

Diver - check your PMs - upper left hand corner next to the User Control Panel.

 

[Diverdown]

I just got back from testing the water since I over shocked it with a boatload of chlorine 3 hours ago

Results are as follows:

CYA 35
TC: 3.5
FC: 3.5
PH 7.4
TA 175
CH 225

I brought two water samples from the pool. The first was taken and brought inside and warmed to 75 deg naturally to remove any stabilizer error associated with the cool pool temp. The second was 3 hours after shocking the pool with 60L of 12% liquid chlorine.

The testing center that the pool company uses is the Bioguard Water Analysis center. To test the stabilizer they used a cyanuric acid tablet removed from a foil wrap that was crushed in a transparent square tube.

For the free chlorine they used DPD-1 tabs and for the total chlorine they used DPD-4 tabs.

The PH test was done using the dropper test.

Test strips were not used.

After the pool was shocked the cover was off and I turned on the stair jets and waterfall. The day is bright and sunny.

Is it usual for the chlorine to drop that drastically after such a short time? I was quite surprised that it was at 3.5 after only a few hours considering the amount of shock that I added.

It appears that the chlorine demand has been satisfied now that free chlorine = total chlorine.

What suggestions do you have to improve the water quality?

I will be adding cyanuric acid to the pool to bring the stabilzier level to 50 and and I will be adding boric acid tomorrow to get the boric acid level to 50ppm as per recommendations on the forum. I think I also need to reduce the TA but is it too soon to do that after shocking the pool?


Thanks

 

[chem geek]

You might consider getting an ammonia test kit from a fish/pet/aquarium store. If your FC got to zero at some point, it's possible bacteria converted some of your CYA into ammonia and that would take a heck of a lot of chlorine to get rid of it -- up to 2.5x the amount of CYA that is lost so 25 ppm FC (cumulatively added) for every 10 ppm CYA.

Also, you can use a bucket test to see the actual chlorine demand where 1 teaspoon of 6% bleach in 2 gallons of pool water would be 40 ppm FC. Of course, you should first find out if you really do have any chlorine in the pool by using an OTO chlorine test (or FAS-DPD test).