Can't maintain FC post Baquacil conversion

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Hello all,

First post here an hoping to get some help. I've searched through a ton of posts in these forums and learned a lot over the past 2 weeks but still having issues.

Opened the pool on May 16th. 14K above ground pool previously on Baquacil. I followed ( or at least I thought i did) the directions for switching from baqacil to Chlorine. I added non chlorine shock at the beginning, filtered 2 days. I added a bit more too at that point as there seemed to be a little baquacil sanitizer still showing on strips. After another day or 2 the pool looked very clear. I started shocking the pool with chlorine. Would immediately turn clear green color. Would clear up, FC would go to zero and I would keep repeating. Eventually stopped turning a clear green with the addition of chlorine. I started adding CYA and currently at 40ppm. I'm worried this is where i went wrong and i added it before i should have in the process. I started adding it because the sun hits my pool strong from 5AM-3:30PM so after a handful of days i assumed the loss of Chlorine was due to not having CYA in the pool. The pool has been crystal clear for 2 weeks. I vacuum any of the debris that might settle and its been overall crystal clear and spotless.

The issue i have been having for almost 2 weeks is that I cannot hold a FC reading for the life of me. I started with 12.5% pool store chlorine, then found walmart 10% to be a better deal (date code is recent). I've been trying to do the SLAM procedure, but the Chlorine loss is so significant. Just an example, its cloudy out right now, FC at 2:30 was 4ppm. I added 1 gallon of 10% which should have increased it to 11.1FC. I tested an hour later (FAS-DPD) and it was back down to 4ppm. Which means I went thru 7ppm in an hour which seems ridiculous. CC was zero. 45 mins later we are at the following:

FC 1
CC O
CYA 40
TA 130
PH 7.0 (currently aerating to hopefully bring up since TA is high)

When the sun is hitting the pool I have no luck ever keeping Chlorine in. Overnight its not terrible but still fairly decent drops. I am going to test again tonight but last night i got it to 15ppm, this morning it was at 5ppm FC, 0CC. I've probably gone through 30-35 jugs of chlorine since starting. I know with the SLAM you are supposed to constantly keep the Chlorine up, but if I'm going though a gallon of bleach every hour in the shade it seems to be a ever failing process. In the end the only thing i can think of is i added CYA too soon in the conversion process, i can't think of anything else. Any help is much appreciated!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
Did you follow TFP's Conversion process or someone else's? TFP never suggests using non-chlorine shock (MPS).



If you add stabilizer (CYA) too soon and there is still baquacil remnants in the water, the conversion will stall. What you're seeing seems to fit that bill since the chlorine loss is so high. There aren't too many ways to fix this but the fastest, and possibly cheapest, way to fix it is to simply drain the pool down to a level that is safe for the liner (typical around 18" of water) and then refill the pool. Then you can follow the TFP conversion process from the beginning and try to get your pool going again.

Did you change the sand in your sand filter?? I don't see that mentioned.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Did you follow TFP's Conversion process or someone else's? TFP never suggests using non-chlorine shock (MPS).



If you add stabilizer (CYA) too soon and there is still baquacil remnants in the water, the conversion will stall. What you're seeing seems to fit that bill since the chlorine loss is so high. There aren't too many ways to fix this but the fastest, and possibly cheapest, way to fix it is to simply drain the pool down to a level that is safe for the liner (typical around 18" of water) and then refill the pool. Then you can follow the TFP conversion process from the beginning and try to get your pool going again.

Did you change the sand in your sand filter?? I don't see that mentioned.

Unfortunately I followed local pool stores guide which told me to use MPS prior to me discovering TFP, so MPS was added. I did change the sand twice now. Once prior to changeover and once after, since i was worried there was baquacil gunk left. I'm assuming the purpose of draining would be to try to get the CYA to zero? Would there be any way to tell if there is baquacil sanitizer left in the pool prior to doing the expense of pool refill? Or is it more than likely this CYA is the culprit. Thanks for taking the time to help.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
I just called my local water utility it would only be about $70 to do the refill so not bad at all compared to what i thought it might be. I should follow the TFP baquacil conversion guide once refilled? (I'm assuming it would go quicker since there really should be little to no sanitizer or CYA at that point). Keep the FC at 15 until overnight loss is 1ppm or less, then it would be safe to add in CYA to 30, keep FC at 15 until CC is 0. Is that pretty much it? I just want to make sure i don't re-add CYA too early. The main goal is little to no loss overnight?
 
Last edited:

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
It’s likely both the oxidation by-products of chlorine breaking down the Baquacil (which you can’t test for) AND the presence of CYA now slowing the entire process to a standstill. Draining will reduce both the CYA and the contaminant load.


Was it also the pool store recommending you change the sand in the beginning?? That wasn’t necessary. I would work with the sand you have now but be prepared to change it again if we can’t get your FC loss rate down.

Draining and refilling is the only reasonable path forward at this point in you ever want to swim in this pool. Once you drain and refill, please follow the procedure outlined above. Unlike a pool with unreacted Baquacil in it, you’ll probably get through the first portion of the conversion fairly quickly.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
It’s likely both the oxidation by-products of chlorine breaking down the Baquacil (which you can’t test for) AND the presence of CYA now slowing the entire process to a standstill. Draining will reduce both the CYA and the contaminant load.


Was it also the pool store recommending you change the sand in the beginning?? That wasn’t necessary. I would work with the sand you have now but be prepared to change it again if we can’t get your FC loss rate down.

Draining and refilling is the only reasonable path forward at this point in you ever want to swim in this pool. Once you drain and refill, please follow the procedure outlined above. Unlike a pool with unreacted Baquacil in it, you’ll probably get through the first portion of the conversion fairly quickly.
Yes sounds like it was overkill. I think the refill sounds like the best path at this point. I could easily spend another $70 on bleach and be in the same situation. Just to be clear that i follow the directions right. I should keep the FC at 15 until overnight loss is 1ppm or less, then it would be safe to add in CYA to 30, keep FC at 15 until CC is 0. Is that pretty much it? I just want to make sure i don't re-add CYA too early. The main goal is little to no loss overnight? Also anything to worry about with draining in regards to liner? Sun or heat or any issues? Assuming drain and refill as quick as possible to avoid issues.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
Yes, 15ppm FC with no CYA until you hold overnight losses to less than 1ppm. Normally at that point you would do a sand change but I would recommend you simply open up the sand filter and deep clean the sand -


Then you will add enough CYA to get your water back up to 30ppm and hold the FC at 15ppm. After 48 hours with CCs < 0.5ppm, you should be good.

You can’t fully drain a liner pool or else the liner will shift and possibly get creases. Typically 18” of water left in the pool is about the lowest you can go. Just drain carefully and watch the liner. If anything looks precarious then stop and refill. It’s better to do two partial drains and waste a lot of water and time than mess up your liner. As long as you drain and refill right away, there shouldn’t be any issues with exposing the vinyl. If the liner is super old, then be very careful as you don’t know how stiff it may have become with age. Just watch it and stop if anything looks like it’s going to go bad.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Current Status:

Drained the pool to 18 inches and refilled. PH 7.4. Brought FC to 15 last night after sun went down. Current FC is 3 at 730AM. There was heavy rain last night for 45 mins and there was about 1.5 hours of early morning sunlight before i got to test it. Still seems like a large loss for fresh water. I just added 1.5 gallons of 12.5% that should bring it up to 15. We'll see how it holds during the day sun.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Tested at 8:30am 15PPM, 9:40am down to 5 PPM. I understand that there's probably little to any CYA left in the pool after the drain but is that reasonable? Pool is clear. Should i continue to dump a gallon of bleach every hour? Seems excessive. Or should i focus more on overnight? I thought i read chlorine can reduce 70-90% in sunlight, which if so i would keep needing to dump chlorine in throughout the daylight just to evaporate.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
Overnight it lost 12ppm FC, that was all from organic contamination. Rain has very little effect.

Are you circulating your pool water? Filter mode or Recirculate mode?

How does the water look - clear or cloudy?

Do you have an opaque tarp you can cover the pool with during the day?

A tarp can help keep the UV from the sun from reducing your FC. But the pool does need to off gas chloramine by products so you do need to uncover it. This is going to take time and LOTS of chlorine to convert your pool. Hang in there. My guess is it is going to be a few days before you see the chlorine holding up overnight.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
I'm keeping the pump on 24 hours a day, its on filter mode. Pool water has been clear, no cloudiness. No increase in filter pressure. Small amount of debris in the middle that I vacuumed out. Its been pretty overcast today since early morning so I'm surprised the chlorine loss is still so much. I added 1.5 gallons of bleach (10%) at 10:45. Just got home and tested at 12:45 and its down to 3 FC. I'll try to keep testing and adding throughout the day. I did just purchase a blue solar cover that I can put on. One thing I noticed is there hasn't been any CC. Does that mean anything since the FC is so high maybe CC won't really show up?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
Keep up the chlorine as best you can. This process takes a lot of chlorine. You’re fighting against a lot of organics and sunlight. Overnight is most important. You can add chlorine during the day and keep the cover on but I’d take it off overnight to let the pool “breathe”.

CCs don’t necessarily form from every chlorine-organic reaction. And yes, without CYA in the water, chlorine will transform (oxidize) organics into very volatile halogenated organics. Eventually it will oxidize most of it to CO2, nitrates and nitrogen gas.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Thanks Matt! I'll try to keep up with it during the day and make sure i keep it at 15 once the sun sets for the overnight tracking. I'll report back over the next few days. I do appreciate all your help!
 
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pookiesunshine

Gold Supporter
May 12, 2016
580
Cincinnati, OH
If you drained down to 18 in and refilled, i'm guessing you diluted cya and any residual baquacil by half or a little more. Have you measured cya after the drain/refill just to confirm what it is now?
great that your water is clear, maybe you have something in your plumbing that is eating chlorine. maybe try running filter on recirculate for a day or two to see if that makes any difference.
also, just to confirm, when you add chlorine, you dont see any color formation that you should have seen when you first started the conversion, correct?
when i did my conversion i found i had residual white mold in my return lines; however, i know this is different since mine is IG and yours is AG and likely has much less plumbing to get contaminated than mine.
 
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Corleone08

Member
Jun 1, 2020
14
Nashua, NH
If you drained down to 18 in and refilled, i'm guessing you diluted cya and any residual baquacil by half or a little more. Have you measured cya after the drain/refill just to confirm what it is now?
great that your water is clear, maybe you have something in your plumbing that is eating chlorine. maybe try running filter on recirculate for a day or two to see if that makes any difference.
also, just to confirm, when you add chlorine, you dont see any color formation that you should have seen when you first started the conversion, correct?
when i did my conversion i found i had residual white mold in my return lines; however, i know this is different since mine is IG and yours is AG and likely has much less plumbing to get contaminated than mine.
I tested CYA this morning and it was under 30 (my test only goes to 30). Not sure how low it actually is, was 40 before. I would have to imagine that if there was any baquacil left it would be a small amount if any. Before the drain i had gone through probably 35 gallons of bleach and had clear water and eventually stopped turning different color when chlorine was added, was completely clear too.

When I add Chlorine there is no change to color whatsoever. Yeah, agreed I don't have much for piping but certainly could be something in there. It's just flexible tube piping so I could replace. I did replace the sand twice now and washed the filter out. After doing the drain the other day I did the deep clean of the filter. Right now the pool is in total shade, added another gallon of bleach and will test in a bit. Curious to see how it does overnight.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
I think I'm starting to show some improvement. Overnight FC loss was only 2, compared to 12 the night before. Tested 16FC at 7pm, was 14FC at 6:45AM. I put the blue solar cover on today which greatly helped keep FC in, still some decent losses during sun coverage but considering there shouldn't be much CYA in the pool not bad, significantly better than the day before without the cover. Pool is now again in the shade and brought up to 15FC. Fingers crossed for tonight!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
I think I'm starting to show some improvement. Overnight FC loss was only 2, compared to 12 the night before. Tested 16FC at 7pm, was 14FC at 6:45AM. I put the blue solar cover on today which greatly helped keep FC in, still some decent losses during sun coverage but considering there shouldn't be much CYA in the pool not bad, significantly better than the day before without the cover. Pool is now again in the shade and brought up to 15FC. Fingers crossed for tonight!
Sounds good. You'll really want to make sure that all of the organics are oxidized. So when you think that your chlorine loss overnight is 1ppm or less, then I would stop using the cover, let it sit open to the sky during a day with 15ppm added in the morning and leave it to burn off in the sun. Covers are great at conserving FC but they can also keep the water from "breathing" a bit and a covered pool will almost always develop CCs if it is not allowed to see the light of day and a good breeze every once in a while. My suggestion about using the cover was to help the process along a bit but it should not substitute for the standard criteria that are outlined in that article (which assumes no covering of the pool). You really want to be absolutely certain that the overnight loss is under 1ppm and then have two straight days of <0.5ppm CCs after the CYA is added. If you follow those criteria, then your pool is definitely a sparkly-clean and properly sanitized pool.

Keep us posted.
 

Corleone08

Member
Jun 1, 2020
14
Nashua, NH
Sounds good. You'll really want to make sure that all of the organics are oxidized. So when you think that your chlorine loss overnight is 1ppm or less, then I would stop using the cover, let it sit open to the sky during a day with 15ppm added in the morning and leave it to burn off in the sun. Covers are great at conserving FC but they can also keep the water from "breathing" a bit and a covered pool will almost always develop CCs if it is not allowed to see the light of day and a good breeze every once in a while. My suggestion about using the cover was to help the process along a bit but it should not substitute for the standard criteria that are outlined in that article (which assumes no covering of the pool). You really want to be absolutely certain that the overnight loss is under 1ppm and then have two straight days of <0.5ppm CCs after the CYA is added. If you follow those criteria, then your pool is definitely a sparkly-clean and properly sanitized pool.

Keep us posted.
Thanks good points, i'll be sure to let the pool breathe. I guess one thing I'm not sure on (skipping ahead here) is how much CYA to actually add after a successful overnight test. I know its currently below 30 based on the test, but i don't know for sure the starting point, and I probably shouldn't assume its as low as 0 in the conversion guidance. I was around 40 before the drain, and drained more than half to get to the 18 inches...so it should be worst case as high as 20, more likely around 13-15. Should I perhaps slowly add increments of 10 until i see it at 30ish? How long does that actually take to show up on a test?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,220
Tucson, AZ
Just calculate the dose you need to increase the CYA by 15ppm. +/- 15ppm is about the tolerance of the test so add 15ppm. Even if your CYA reading looks like it's between 30ppm and 40ppm, you can call it 40ppm CYA and then we can adjust the FC you need to add (it'll be more like 16ppm or so).

We typically recommend that people buy granular CYA because it is the cheapest form. Then you load up a ladies nylon or an old thin dress sock with the dose you need and hang it in front of a return. You can knead the sock every couple of hours or so to help it dissolve (granular CYA dissolves very slowly). However, if you like to spend money, you can buy the stuff people refer to on here as "Liquid Gold" - it's a liquid form of CYA that you can pour right into your skimmer and it will disperse and completely mix probably within an hour. However, it is typically 3X more expensive than granular as it is only ~ 30% by weight cyanuric acid. SO, if you value convenience and speed over cost, feel free to buy the liquid gold.