I now see the threads discussing Baquacil CDX and CCs that hang on for weeks or months after conversion. We did not have that... It seemed like a normal conversion story, and we are currently not experiencing any significant CCs despite the current rapid FC loss.
Full sun, clear cover, CYA 55... And FC zero by end of day after SLAM
- Thread starter themitzelfamily
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When you are doing the overnight chlorine loss test and your last testing in the evening are you taking the sample after the pump has ran at least 30 min?
I converted my pool last year from Baquacil to TFPC last year. (and I had used the CDX)
However I had a similar problem with the FC level dropping out rapidly in the sun. Because of that my conversion took a long time. I covered the pool 80-90% to mitigate the loss(s). I tried (several) control 5 gallon bucket test of pool water and let it set in the garage for 24hrs and it would hold its FC level (and CYA was 50). I would take the bucket out in the sun and in a short time the FC was basically gone (I don't remember the numbers).
Finally FC started to hold during daylight. So I have read most of Baquacil conversions here and they seem to be text book ...clean out goo etc ... then all OK. Mine did not. I just chalked up my experience as I must have done something wrong somehow. But now counting my own, yours makes the third Baquacil conversion that I have read here that has had the Sunlight issue. I don't believe most Baquacil users use the CDX product. I am a mechanical engineer not a chemist but it seemed to me "like" something else was binding with CYA (thereby blocking the chlorine from binding).
I could be nuts.
However I had a similar problem with the FC level dropping out rapidly in the sun. Because of that my conversion took a long time. I covered the pool 80-90% to mitigate the loss(s). I tried (several) control 5 gallon bucket test of pool water and let it set in the garage for 24hrs and it would hold its FC level (and CYA was 50). I would take the bucket out in the sun and in a short time the FC was basically gone (I don't remember the numbers).
Finally FC started to hold during daylight. So I have read most of Baquacil conversions here and they seem to be text book ...clean out goo etc ... then all OK. Mine did not. I just chalked up my experience as I must have done something wrong somehow. But now counting my own, yours makes the third Baquacil conversion that I have read here that has had the Sunlight issue. I don't believe most Baquacil users use the CDX product. I am a mechanical engineer not a chemist but it seemed to me "like" something else was binding with CYA (thereby blocking the chlorine from binding).
I could be nuts.
Oldpoolboy2, this sounds like what we are dealing with... It may have been that we were always losing all our chlorine (maybe not all gone on non-sunny days, but I never picked up on the corelation). So weird. Thanks for saying it eventually does start to hold daytime FC. We have been feeling crazy... I am a biologist and no stranger to lab testing, and my DH is also a Mech Engineer. We're not crazy, but our results sure are! I read in a differrent forum about a couple cases of CDX issues during conversion, but they dealt with lots of inexplicable CCs during/after conversion. Chem Geek talked about CDX as a chemical substance similar to borates, but without being attached to chlorine or bromine... So maybe that is part of the issue. I don't know much and there certainly doesn't seem to be a lot of cases of this, so who knows. Deep sigh. This too shall pass.
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April: We leave the pump on 24/7 during a SLAM, so yes it is well mixed for night readings.
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April: We leave the pump on 24/7 during a SLAM, so yes it is well mixed for night readings.
Sure hope chem geek jumps in on this one.
If I had to guess, from all the stuff I've read, maybe the CDX binds with CYA or maybe it pretends to be CYA. So you think you are reading X amount of stabilizer but it's really the left over CDX??
If I had to guess, from all the stuff I've read, maybe the CDX binds with CYA or maybe it pretends to be CYA. So you think you are reading X amount of stabilizer but it's really the left over CDX??
I am inclined to believe our CYA readings are good... We put in a total of 64 ppm CYA over two doses since the conversion, and have had some dilution so 50-60 seems right. But still.... It's not acting right...
CDX as shown this MSDS is mostly 5,5-Dimethylhydantoin (DMH) which is the core chemical in bromine tabs.
We don't have any equilibrium constants of DMH with chlorine, but it may be that at rather high DMH (from CDX) concentrations that it binds more to chlorine than CYA does and if that is the case then maybe such chlorine bound to DMH is susceptible to breakdown from the UV in sunlight. Perhaps this also helps break apart DMH itself so eventually the problem dissipates. Also, since you report overnight losses as well maybe higher chlorine levels help to break down DMH itself though that is speculative.
We don't have any solutions for this except to 1) dilute the water to remove the DMH (CDX) or 2) SLAM to accelerate oxidation of the DMH. Increasing the CYA level to shift the equilibrium more towards chlorine attaching to CYA than to DMH may help protect the chlorine from breakdown from sunlight, but it won't keep active chlorine around so you could get algae growth. Also, when the DMH does eventually go away, you'll have too high a CYA level.
This may mean that we shouldn't be recommending chlorine conversions of Baquacil when CDX was used, especially if used a lot or for a long time. We should either be recommending drain/refill or possibly the use of sodium percarbonate which is another approach to oxidizing Baquacil, BUT we don't know if it will also get rid of CDX. If you are willing to be a guinea pig, then it's something you could try. It would wipe out chlorine because sodium percarbonate in water results in a combination of sodium carbonate (i.e. pH Up) and hydrogen peroxide. If nothing else, at high concentrations and in sunlight this would produce hydroxyl radical that are very short-lived but powerful oxidizers that should get rid of both Baquacil and DMH. I see that you can get sodium percarbonate online from Amazon for around $2.35 per pound (it's also available from The Chemistry Store but seems more expensive). The normal amount used in Baquacil conversions is one pound per 2000 gallons so for a 30,000 gallon pool that would be 15 pounds. You'd lower your pH first (to around 7.2) before using this since it significantly raises the pH.
However, this is speculative as to whether this would work but if your only other option (other than waiting it out with a lot of chlorine use) would be drain/refill then it may be worth a try. The good news is that one can easily recover from using sodium percarbonate in their pool because acid will adjust the pH and adding chlorine will get rid of the hydrogen peroxide that is leftover. If none of the hydrogen peroxide reacted, then the one pound of sodium percarbonate is equivalent to 0.675 pounds of sodium carbonate and 0.325 pounds of hydrogen peroxide which in 2000 gallons would require around 37 ppm FC to get rid of.
[EDIT] Maybe you can do a bucket experiment with small quantities of sodium percarbonate to see if it would work and if it does then can use it in the pool. 1 pound per 2000 gallons would be 0.008 ounces (0.23 grams) per gallon so in a 5 gallon bucket would be 0.04 ounces (1.13 grams) so 1/4 teaspoon in 5 gallons. [END-EDIT]
We don't have any equilibrium constants of DMH with chlorine, but it may be that at rather high DMH (from CDX) concentrations that it binds more to chlorine than CYA does and if that is the case then maybe such chlorine bound to DMH is susceptible to breakdown from the UV in sunlight. Perhaps this also helps break apart DMH itself so eventually the problem dissipates. Also, since you report overnight losses as well maybe higher chlorine levels help to break down DMH itself though that is speculative.
We don't have any solutions for this except to 1) dilute the water to remove the DMH (CDX) or 2) SLAM to accelerate oxidation of the DMH. Increasing the CYA level to shift the equilibrium more towards chlorine attaching to CYA than to DMH may help protect the chlorine from breakdown from sunlight, but it won't keep active chlorine around so you could get algae growth. Also, when the DMH does eventually go away, you'll have too high a CYA level.
This may mean that we shouldn't be recommending chlorine conversions of Baquacil when CDX was used, especially if used a lot or for a long time. We should either be recommending drain/refill or possibly the use of sodium percarbonate which is another approach to oxidizing Baquacil, BUT we don't know if it will also get rid of CDX. If you are willing to be a guinea pig, then it's something you could try. It would wipe out chlorine because sodium percarbonate in water results in a combination of sodium carbonate (i.e. pH Up) and hydrogen peroxide. If nothing else, at high concentrations and in sunlight this would produce hydroxyl radical that are very short-lived but powerful oxidizers that should get rid of both Baquacil and DMH. I see that you can get sodium percarbonate online from Amazon for around $2.35 per pound (it's also available from The Chemistry Store but seems more expensive). The normal amount used in Baquacil conversions is one pound per 2000 gallons so for a 30,000 gallon pool that would be 15 pounds. You'd lower your pH first (to around 7.2) before using this since it significantly raises the pH.
However, this is speculative as to whether this would work but if your only other option (other than waiting it out with a lot of chlorine use) would be drain/refill then it may be worth a try. The good news is that one can easily recover from using sodium percarbonate in their pool because acid will adjust the pH and adding chlorine will get rid of the hydrogen peroxide that is leftover. If none of the hydrogen peroxide reacted, then the one pound of sodium percarbonate is equivalent to 0.675 pounds of sodium carbonate and 0.325 pounds of hydrogen peroxide which in 2000 gallons would require around 37 ppm FC to get rid of.
[EDIT] Maybe you can do a bucket experiment with small quantities of sodium percarbonate to see if it would work and if it does then can use it in the pool. 1 pound per 2000 gallons would be 0.008 ounces (0.23 grams) per gallon so in a 5 gallon bucket would be 0.04 ounces (1.13 grams) so 1/4 teaspoon in 5 gallons. [END-EDIT]
Wowza. Thanks for all that info, chemgeek! I will talk to my DH and see what we're up for. Our initial baqua conversion was probably close to 100 gallons of varying concentrations of chlorine, and this last bout has been 40 gallons at least. And the water looks pristine, which feels like a slap in the face of trying to DIY this invisible problem. Meh. So far this hasn't actually been cheaper than Baqua... Going on faith that one day it will be...
I wonder if I take a sample of our pool water to the pool store and have them test for CDX... If having a known value would give us something to start at to see if we are making any progress on getting rid of it. Though we might be at a place where draining and refilling would be the best option for our situation. We have well water (free except for pumping it) and when it was tested we can see that it shouldn't be a problem to get to acceptable levels in terms of iron/TA, etc, and as we are going out of town for 10 days it might be considerably more economical than dealing with trying to chlorinate a pool that refuses to be chlorinated, not to mention the effort of getting rid of CDX.
We lost 3 ppm last night (10 ppm down to 7), and we're swimming later but we'll add a full shock tonight and keep it up for the next 72 hours-ish until our next scheduled pool party.
I wonder if I take a sample of our pool water to the pool store and have them test for CDX... If having a known value would give us something to start at to see if we are making any progress on getting rid of it. Though we might be at a place where draining and refilling would be the best option for our situation. We have well water (free except for pumping it) and when it was tested we can see that it shouldn't be a problem to get to acceptable levels in terms of iron/TA, etc, and as we are going out of town for 10 days it might be considerably more economical than dealing with trying to chlorinate a pool that refuses to be chlorinated, not to mention the effort of getting rid of CDX.
We lost 3 ppm last night (10 ppm down to 7), and we're swimming later but we'll add a full shock tonight and keep it up for the next 72 hours-ish until our next scheduled pool party.
themitzelfamily Those amounts of chlorine seem similar to what I used. I wrote in another post that adding and adding chlorine was like treating someone with a bad fever, you try to control it and it seems like nothing works put you keep trying then eventually the fever breaks.
Even with the very large volume of chlorine used It was still less expensive for me than baquacil. 2 of my children would get a rash in the Baq pool. The current chlorine (TFP) no smell, no rash, no eye sting, no halo around lights. I get comments now like "wow that pool is crystal clear". I am a avid advocate of the TFPC methods.
Given what I know now in hindsight I would have drained and refilled the pool, it would have been the least amount of greif ... but I wanted to see if the TFPC methods worked. And I learned so much.
Chem Geek... thank you for jumping in on this, I feel a great deal of redemption in that I may not have been nuts (my friends might disagree).
Bill
Even with the very large volume of chlorine used It was still less expensive for me than baquacil. 2 of my children would get a rash in the Baq pool. The current chlorine (TFP) no smell, no rash, no eye sting, no halo around lights. I get comments now like "wow that pool is crystal clear". I am a avid advocate of the TFPC methods.
Given what I know now in hindsight I would have drained and refilled the pool, it would have been the least amount of greif ... but I wanted to see if the TFPC methods worked. And I learned so much.
Chem Geek... thank you for jumping in on this, I feel a great deal of redemption in that I may not have been nuts (my friends might disagree).
Bill
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Idk, if I would continue to shock at this point, until you decide what you are gonna do...
{I know that traditional wisdom is Cl loss is organic or sun... But in the face of a baqua conversion+ CDX situation, that statement may not be so clear-cut
}
So absolutely, you need to keep FC above the min for CYA-- but to my mind, shocking is a waste, especially if you end up just draining and refilling soon. You did say there's no visible algae, right? Any slimy-feeling or slippery patches, even if you can't see any discoloration?....
To cover all the bases: did you clean out every, sneaky hiding spot for the bacqua-nasties, or algae (behind lights, in ladder tubes, etc.)?
I know it's hard to believe when you keep having to buy so much liquid chlorine, but it will be cheaper in the long run.
One pink slime &/or white mold outbreak, and you would spend more on bacqua products than a year of shocking* with Cl would cost ---And it would probably never really be gone...
Once you are over this new "bump", you too, can have (and keep) a clean, safe & pretty TFP.
*a year of shocking would never, ever be necessary... The comment was (slightly) exaggerated & for comparison purposes....
As for vacation:
ChemGeek, could they add some P-60 (so they don't come home to an algae pit), put the cover on the pool and deal with everything when they get back?
{I know that traditional wisdom is Cl loss is organic or sun... But in the face of a baqua conversion+ CDX situation, that statement may not be so clear-cut
}So absolutely, you need to keep FC above the min for CYA-- but to my mind, shocking is a waste, especially if you end up just draining and refilling soon. You did say there's no visible algae, right? Any slimy-feeling or slippery patches, even if you can't see any discoloration?....
To cover all the bases: did you clean out every, sneaky hiding spot for the bacqua-nasties, or algae (behind lights, in ladder tubes, etc.)?
I know it's hard to believe when you keep having to buy so much liquid chlorine, but it will be cheaper in the long run.
One pink slime &/or white mold outbreak, and you would spend more on bacqua products than a year of shocking* with Cl would cost ---And it would probably never really be gone...
Once you are over this new "bump", you too, can have (and keep) a clean, safe & pretty TFP.
*a year of shocking would never, ever be necessary... The comment was (slightly) exaggerated & for comparison purposes....
As for vacation:
ChemGeek, could they add some P-60 (so they don't come home to an algae pit), put the cover on the pool and deal with everything when they get back?
We've got 10ish days before the 10 day vacation, and have never drained/refilled, so this would be new territory too. I planned to look into that tonight. My DH is sad at that prospect since it finally got up to a nice temp ah well. I wonder if we can dump and refill before we go, then SLAM with a lower level of CYA, cover it and add pucks to chlorinate and up the CYA back to full sun proportions while we're gone. That might keep it clean without needing outside maintenance and allow it to heat up a bit as well over the time we're gone.
At present, it does keep FC when in darkeness, so we will keep dosing it and monitoring FC loss under the cover. I really don't want anyone to get sick from swimming in it.
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AprilsZoo: No visible algae, no slime. We're vacuuming and brushing every time we swim and I cleaned out the light niche and other trouble spots earlier in the week. Thanks for the thoughts. Good question about the p-60... Been wondering about that myself...
ah well. I wonder if we can dump and refill before we go, then SLAM with a lower level of CYA, cover it and add pucks to chlorinate and up the CYA back to full sun proportions while we're gone. That might keep it clean without needing outside maintenance and allow it to heat up a bit as well over the time we're gone. At present, it does keep FC when in darkeness, so we will keep dosing it and monitoring FC loss under the cover. I really don't want anyone to get sick from swimming in it.
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AprilsZoo: No visible algae, no slime. We're vacuuming and brushing every time we swim and I cleaned out the light niche and other trouble spots earlier in the week. Thanks for the thoughts. Good question about the p-60... Been wondering about that myself...
I just read the whole awful thread of aciam's conversion (here: aciam - Nightmare conversion from baquacil to chlorine). A lot of that sounded like what my DH described. I was not very involved in last year's baqua maintenance or the conversion and early maintenance this year with chlorine. Our FC/CC tests sound like hers in that the FC test, once complete and at a clear state, if left for any kength of time would revert to pink or even a deeper purple shade. My hypothesis on that is that the chlorine present in the vial is eaten/changed by sunlight over time (rapidly, even) and the resulting liquid in the vial reflects that in the color change. Maybe?
Today I tested the water before pulling off the opaque tarp (we were letting the FC drop with plans to swim in the evening). First test was 6:10 PM, FC 3.5. Second test was 15 minutes later and FC was 2. Loss of 1.5 ppm in 15 minutes (at 6PM with very slanted sunlight and some minor shade on the pool... We're not talking midday sun).
Our current plan is to drain/refill this Sat night after a previously scheduled party. Pool is currently covered with opaque tarp and we are going to simply try to maintain it at or above the target FC, in darkness, until we want to swim at which point all FC will rapidly drop to zero. After swimming we will up the FC again. Tonight it is at 12 ppm (CYA 60ish). I see no point is bringing it to shock level only to lose it all to sun. Is that waaay unsanitary? It's certainly not ideal, but we just need to make it to Sunday...
Today I tested the water before pulling off the opaque tarp (we were letting the FC drop with plans to swim in the evening). First test was 6:10 PM, FC 3.5. Second test was 15 minutes later and FC was 2. Loss of 1.5 ppm in 15 minutes (at 6PM with very slanted sunlight and some minor shade on the pool... We're not talking midday sun).
Our current plan is to drain/refill this Sat night after a previously scheduled party. Pool is currently covered with opaque tarp and we are going to simply try to maintain it at or above the target FC, in darkness, until we want to swim at which point all FC will rapidly drop to zero. After swimming we will up the FC again. Tonight it is at 12 ppm (CYA 60ish). I see no point is bringing it to shock level only to lose it all to sun. Is that waaay unsanitary? It's certainly not ideal, but we just need to make it to Sunday...
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i think 12ppm fc is a perfect plan for your situation.. It also sounds like you have a good plan.. sorry you have to drain and refill but it looks like that may be your best option...
For starters, can post a picture of how the pool looks and a current set of results. Something very odd is happening and as stated I too wonder about the CDX product.
For starters I'd suggest using a dose of Polyquat 60 to add some insurance against algae. It's going to add some extra cost (around $20) but you likely will benefit greatly. To help get to Sunday at least, I'd suggest raising the FC after sunset to help kill off anything as you are planning. From there we'll try to pinpoint the issue further.
To clarify: by "P-60", I meant Polyquat 60...
I wasn't sure if it was compatible with the CDX product that the OP (can we call you "TMF"?) had used in the past.
I thought it might be fine, but wanted to leave that call up to one of the "Experts". Richard, a.k.a. ChemGeek, is just who I thought of first.
I wasn't sure if it was compatible with the CDX product that the OP (can we call you "TMF"?) had used in the past.
I thought it might be fine, but wanted to leave that call up to one of the "Experts". Richard, a.k.a. ChemGeek, is just who I thought of first.
I think as long as you have Cl in the pool appropriate to your CYA level, then after letting mix for about 30 mins or so, your water will be sanitary.
However, assuming your party is going to last longer than it has been taking your FC to reach zero... Then you will have to make periodic Cl additions during your party to keep it that way (sanitary)...
Killing everything so that it's safe to get in, is one thing... But you will need some residual FC available to kill what gets brought in by swimmers--- notably fecal bacteria, among others... its just a fact of life that we all carry with us.
And if it were me, I'd request that anyone who's sick stay out of the pool �� It might be overkill, but better safe than sorry.
It should be compatible, but we don't have direct experience with that combo since there are so few pools that have had CDX (we get a limited number of Baquacil conversions each year and most don't use CDX). Polyquat 60 would help prevent algae growth when the chlorine went to zero. It won't stop it completely but it will slow it down.
Thanks, yet again for reading/posting. You can call me TMF
Leebo, I am not going to post a pic because the pool is covered, but it is CLEAR. Beautiful, not a hint of green.
Currently we are keeping FC at above the target for our CYA (60 ppm)... Last night I brought it up to 17 ppm (0 CC), and we are just keeping it under the opaque cover today and tomorrow until swim time. AprilsZoo, I did let our guests know the situation and requested no sick people swimming and only kids old enough to be trusted not to poop in the pool The only issue with adding FC during the swim is that it would be gone before it could really do anything anyway, unless it's after dark. Here is where an ozonator might have been helpful.
We have lined up to borrow a pump to aid our drain on Saturday evening. Hoping that goes smoothly. Any good threads here on best practice for draining/refilling gunnite pools would be helpful. The land drops away from our house/pool and it's been dry here for the past couple weeks, but of course it's still a scary thing to DIY.
My feeling on this is that, in hindsight, I wish we had drained from the get-go. But we have learned a lot in the mean time and that is certainly worth something I am looking forward to the day when our chemistry acts like it should!
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My other thought was that, without FC, this is basically a giant kiddie pool. Like the shallow inflatable ones I let my swim-diaper-clad toddlers tromp around in. No chlorine, and we didn't change the water every day. So may be I shouldn't freak out about a pool party starting in clean water but with no circulating FC, or maybe I should freak out about how unsanitary it was back in the day All those bullets we dodged!
Leebo, I am not going to post a pic because the pool is covered, but it is CLEAR. Beautiful, not a hint of green.
Currently we are keeping FC at above the target for our CYA (60 ppm)... Last night I brought it up to 17 ppm (0 CC), and we are just keeping it under the opaque cover today and tomorrow until swim time. AprilsZoo, I did let our guests know the situation and requested no sick people swimming and only kids old enough to be trusted not to poop in the pool
The only issue with adding FC during the swim is that it would be gone before it could really do anything anyway, unless it's after dark. Here is where an ozonator might have been helpful.We have lined up to borrow a pump to aid our drain on Saturday evening. Hoping that goes smoothly. Any good threads here on best practice for draining/refilling gunnite pools would be helpful. The land drops away from our house/pool and it's been dry here for the past couple weeks, but of course it's still a scary thing to DIY.
My feeling on this is that, in hindsight, I wish we had drained from the get-go. But we have learned a lot in the mean time and that is certainly worth something
I am looking forward to the day when our chemistry acts like it should!- - - Updated - - -
My other thought was that, without FC, this is basically a giant kiddie pool. Like the shallow inflatable ones I let my swim-diaper-clad toddlers tromp around in. No chlorine, and we didn't change the water every day. So may be I shouldn't freak out about a pool party starting in clean water but with no circulating FC, or maybe I should freak out about how unsanitary it was back in the day
All those bullets we dodged!Well, one of our kids got an ear infection... Might be from the pool, might not. Either way, we cancelled the week's swimming plans and are draining right now. Almost at the bottom of the steps...