Can't get Chlorine to hold

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Hello all,

I've been having a heck of a time to get the pool to hold chlorine after the ascorbic acid treatment. I've tried following the directions from TFP and bring it up slowly, but it wasn't even registering. Used some Algaecide40 to prevent and algae blooms, and followed up with some stain/scale sequestrant. Pool water is crystal clear currently but won't hold chlorine.

FC 0.0
TC 0.0
Ph 7.2
TA 110
CYA 35
CH 294

I started trying to bring it back up with small doses of granular pool shock, no dice. Then tried some liquid chlorine and it didn't register, so I tried more (5L bottle) to try to kick start it. Did a test 5 hr later and chlorine was very high (off chart of tester 10+) and PH (8.2) was now as well. Before bed last night put in some dry acid to bring down PH and planned to let sun burn off some chlorine in the sun the next day. Woke up, tested and FC was back to 0.0 and PH was 7.2.

I looked at maybe raising the CYA but read that it kills the chlorine's effectiveness at killing bacteria so I am hesitant as I didn't have a problem holding FC level previously.

I'm lost now. I don't really want to waste more $$ on chlorine and other chemicals if it won't hold... Please help.

Thx
 
Last edited:

justinc

Gold Supporter
Apr 3, 2019
585
Texas
Can you list the ingredient in your algaecide 40?

Are these results from a pool store? How are you testing your water?

If your algaecide 40 is ammonia based, every drop of chlorine you put in will bind up with the ammonia until it's all gone. Along with the ascorbic acid which needs to be broken down by the chlorine.

Your chlorine needs will be greater than usual because you have just put a bunch of stuff in the pool that needs to be oxidized. Just stay at it and add slowly and keep checking with a reliable kit (TF-100 or K2006... NOT pool store tests)
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Thanks for the responses. I am using a 4 way drop test kit. I don't know the brand name of it, can't see one.

The Algaecide40 was a Aquarius product from Canadian Tire.
Ingredients: Poly [(oxyethylene dimethylimino) Ethylene-(dimethylimino) Ethylene Dichloride]: 40%

Is it strange that the chlorine held for like 5 hours last night at a very high number but then once the PH was lowered (with PH down) it dropped off to zero again?

Do I need to add more CYA so the chlorine will hold?

Sorry it seems crazy that after putting so much chlorine in for the last week that it's still not registering. I feel like I'm just throwing $$/chemicals away with no results.

I'll keep adding some chlorine in and hope it takes. How often should I be adding it in and rechecking? Should I hold off adding anything else until chlorine takes?

Side note: I found some white flakes that disintegrated when you try to pick them up. Could that be from all the chlorine I've been putting in? Should I add some stain & scale sequestrant?

Side side note: if you haven't guessed, I'm new to pools. This is new since spring for us. Trying my best but it's getting the better of me lately!😬 Need to have it good to go for the kids lessons on Monday.

Thx again for all the help.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
Why are you lowering pH so much? Any pH in the 7s is fine.

Don’t add anything other then CL. Don’t add CYA yet. Don’t add stain & scale sequestrant.

Can’t hold chlorine and low pH is a sign you have ammonia. Keep adding chlorine until you break it.
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Why are you lowering pH so much? Any pH in the 7s is fine.

Don’t add anything other then CL. Don’t add CYA yet. Don’t add stain & scale sequestrant.

Can’t hold chlorine and low pH is a sign you have ammonia. Keep adding chlorine until you break it.
The PH was 8.2+, hence lowering it as per the Ascorbic Acid guidelines to around 7.2.

I'll start adding chlorine.
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Ascorbic acid for stains -> then trying to get chlorine to hold for a week now.

Followed the RFP Ascorbic acid guidelines (likely used more Ascorbic acid than needed), chlorine not taking after a week.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Yes, those ones. But chlorine not coming back within a week. I've put tons in the pool over the last week....
 
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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
Yes, those ones. But chlorine not coming back within a week. I've put tons in the pool over the last week....
You say you overdid the AA. Quantify tons?

Without a good test kit with a FAS/DPD Chlorine test I am not sure you can really know where you stand.
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
Yes, those ones. But chlorine not coming back within a week. I've put tons in the pool over the last week....
Also, I added the sequestrant because the stains were coming back. As they are now again. If I don't add some sequestrant until Chlorine holds, will the sequestrant remove them later? Or is it a lost cause
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
The only permanent way to get metals out fo the pool is by draining the water while the metals are held in the sequesterant. Once the metals drop out of the sequesterant and stain the pool it will take another AA cycle to release it and capture it in the sequesterant. The sequesterant eventually degrades and you have to constantly renew the sequesterant to keep the metals in suspension if you don;t drain it out.
 

ScubaDoo

Well-known member
Jul 3, 2019
78
Great Lakes
You say you overdid the AA. Quantify tons?

Without a good test kit with a FAS/DPD Chlorine test I am not sure you can really know where you stand.
I used one jug (800g) of Stain Free didn't see the stains lift... then about 1000g of ascorbic acid from health food store. Stains lifted.

For amounts for Chlorine...
Then, started slow using bleach 1.89L to raise it to FC 2.0. No sign of FC, out of bleach I switched to the granular shock I had
(70% calcium hypochlorite) using about 250g every few hours for a few days. No FC readings. Added some sequestrant in there as stains started to reappear. getting worried about algae I bumped up to 150g per 10000L (150x8). Did that for a two days to try and get rid of AA... But FC still zero. Ran out of the granular, went and bought some liquid chlorine at 10.3%. Started with 1L a couple time in a day, nothing so I went for a whole jug (5L) the next afternoon. Came back around 11pm and finally got a FC reading. It was 10+ on the tester and PH was 8.2+. So added 1500g of dry acid to reduce PH and I'd let the Chlorine slowly burn off in sun the next day. Went to test it in the morning and the FC was zero. PH was 7.3.

As of today after dinner, added 2.75L of liquid again... How soon can I test and get an accurate reading to see if it's holding?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
ok, you now described your sequence of events. You added too much chlorine too quickly. Adding lots of LC qucikly will raise the pH. In addition once FC gets above 10 the pH test is not valid. You do not have a test kit that can properly measure FC, especially when it is above 10.

To critique what you did you did not follow this:

After 24 hours you can start to rebalance the water. Bring up your ph and alkalinity, - use arm and hammer washing soda first, it will raise both ph and alk. Make sure you test in between, because you don't want your ph to go any higher than 7.2. If your alkalinity is in range, and you still need to raise your ph, use Borax to take it up to no higher than 7.2. You can start to bring up your chlorine. You want to do this slowly. It will take a lot of chlorine - I prefer to use bleach only at this time, and try to take it up to your minimum chlorine for your cya according to the Chlorine / CYA Chart - Trouble Free Pool. As you slowly raise the chlorine, watch for stains starting to form. If you see stains, make sure the ph is no higher than 7.2, and add more sequestering agent. You should see the stain lift in a couple of hours. Do not shock! Do not shock for at least 2 weeks! Make sure you keep your ph low for (7.2) for a week or two - it won't be hard because the ascorbic acid and sequestering agent will help it stay low. Once your chlorine starts to hold, it means that you have used up the ascorbic acid in the water and it will be easy to rebalance the pool back to your regular parameters.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
How do your stains now compare with when you started?

I think if you shock the pool all the stains will return.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
6,617
Northern NJ
We don't shock pools using TFP methods. Using shock adds unwanted CYA to the pool.

I would get a proper test kit.

Continue to slowly add liquid chlorine to break the AA. Once you are holding chlorine you can see where you are and decide if youw ant to try another cycle of AA.