Disappearing CYA

I tried posting this over at TFP but I keep getting an error so ...

I'm having a problem with no CYA in the pool along with algea which I believe is due to no CYA. I opened the pool to 0 CYA and used trichlor to get the CYA to 35. I hadn't tested the CYA all season as in past seasons it usually is the same.

I have been having an algea problem for the past few weeks and haven't been able to solve it. I have been home the past few days and have been concentrating on solving the algea. I've been putting chlorine in and checking every few hours and it reads 0, I assumed it was being eaten by whatever in the pool. On a whim today I tested the CYA and found it to be 0.

I haven't drained the pool and whatever rain we had didn't cause the pool to overflow a lot (AG pool) so I am at a loss. I did put some stain remover in that seemed to be acid based and it had me drop the PH to 7 (I might have gone lower). I will be adding CYA to the pool but I am wondering on what's going on?

Any feedback on this is appreciated!

Thanks!!

Vinny

There has been some discussion in the past on this forum about the ability of an extended algae outbreak to break down the CYA. I think chemgeek or waterbear put a detailed explanation of why this happens somewhere, but in layman's terms, your algae bloom has probably degraded your CYA to zero. Given this condition, you're going to lose as much chlorine to the sun as to the algae, so you're fighting a losing (and expensive) battle. I would add enough CYA in one dose (it'll take weeks if you just use trichlor) to get your pool up to about 20 ppm, and in the meantime raise your chlorine to shock level and keep it there by testing and adding more every few hours like you've been doing. Keep in mind that your chlorine is going to be much more effective if you'll add it at night because the sun's not consuming it, and that it'll take a week or so for your CYA to completely dissolve, so you're going to have to be pretty consistent with your testing and bleach additions to clear up the bloom.

Janet

Thanks!

I went and bought stabilizer, added it to hot water and added it to the pool. I also have put in trichlor pucks and will monitor the pool as much as possible.

I will continue to add beach and keep the chlorine at high levels.

Quote:

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Originally Posted by vinnygnj

I also have put in trichlor pucks and will monitor the pool as much as possible.

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Keep an eye on your pH, especially if you started at 7.....the trichlor is going to drive it further down.

Janet

Janet,

Thanks for the reminder!

There was some mis-communication on my part ... I dropped the PH to 7 for the stain remover and then brought it back up 24 hours later to 7.6 and hopefully locked it in with baking soda so it should stay for a while.

Thanks again!

Vinny

Trichlor is the wrong product for this problem.

Go to Sams Club and buy the big three pack cases of 1.5 gallon jugs Clorox.

In Western PA they cost $7.50 per case.

SHOCK YOUR POOL WITH CHLORINE BLEACH UP TO ABOUT 15 ppm at night.

Do this a couple of nights in a row. I have an inground pool and had the same problem you are experiencing with CYA loss.

It took me about 50 gallons of bleach over a two week period to fix it. This problem stems from not consistently maintaining an appropriate chlorine level.

You simply have to burn the ammonia out of the pool. It will take time but your pool will come around. I would not add any CYA till you get the chlorine level consistently stablized.

Also, all this bleach is going to send your alkalinity through the roof. You should aerate during the entire process to keep your water churning.

THis happened to me at the beginning of this swim season. I opened to a swamp, and got the water cleared up pretty quickly with bleach, but had an awful time holding the chlorine overnight. I put in stablalizer, to get it up to 30, and kept adding bleach to take it back to shock levels everytime I could test. It took a good 2 - to 2 1/2 weeks for it to hold chlorine overnight. I don't even know how many gallons of bleach I used:D Even though the water looked crystal clear, and there showed no cc, it still needed lots of bleach to get the water to hold the chlorine overnight. My water has been fine since:cool:

Quote:

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Originally Posted by chemicalbalance

Trichlor is the wrong product for this problem.

Go to Sams Club and buy the big three pack cases of 1.5 gallon jugs Clorox.

In Western PA they cost $7.50 per case.

SHOCK YOUR POOL WITH CHLORINE BLEACH UP TO ABOUT 15 ppm at night.

Do this a couple of nights in a row. I have an inground pool and had the same problem you are experiencing with CYA loss.

It took me about 50 gallons of bleach over a two week period to fix it. This problem stems from not consistently maintaining an appropriate chlorine level.

You simply have to burn the ammonia out of the pool. It will take time but your pool will come around. I would not add any CYA till you get the chlorine level consistently stablized.

Also, all this bleach is going to send your alkalinity through the roof. You should aerate during the entire process to keep your water churning.

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I disagree. Without CYA in the water, then most if not all the bleach she adds during the day will be lost to sunlight. I stand by my advice to go ahead and add the stabilizer since it takes a little time to completely dissolve. The poster has already stated that she is keeping her chlorine levels high usng bleach during this process, so delaying the addition of CYA makes no sense. Also, adding bleach to a pool does not necessarily raise total alk, and even if it did, aeration is not going to lower it. Acid lowers the alk, aeration raises the pH without an accompanying increase in alk.

Janet

It seems that the chlorine is being maintained. I put bleach in this morning and went out for the day. I came home and after a day of some sun (I think) and rain it was well over 5 (based on the color) using a Taylor K-2005 kit.

I left it to see if in the morning it is above 5 or not. If it is I will dilute the amount to get a more accurate reading if not in goes more bleach.

My PH took a dive yesterday after adding the stabilizer and at this point it's at 7.4, so hopefully I'll be in the clear and things will start working the way they used to!

I do have a question though about the amonia - chlorine and amonia are supposed to combine for CC - I never got CC in my pool. I would imagine that after a night of killing and combining with amonia that the CC would be through the roof in the morning - I don't think my pool had a lot of amonia in it.

Thanks!

Vinny

BTW, I am a he, not a she ... how many Italians named Vinny do you know are shes? ;) LOL!!!!

I think the problem is solved!

After testing the water this morning, the chlorine was at around 5, I added some more bleach and in the NJ hazy sunlight the chlorine level was still above 5.

I only added 4 lbs of stabilizer and by my calculations (13, 000 gallons) it should only be at about 30 to 35 (unfortunately the store ran out of testing reagent) if it's all disolved. I would imagine at the rate I was losing chlorine before adding the stabilizer that the chlorine is going towards killing the algea now, if any is alive. I did add some more bleach to give the existing chlorine a boost. Hopefully my pool will go back to normal.

Thanks for the help!

Vinny

Glad it's starting to clear up for you. If you add your chlorine at night, then retest in the morning before the sun has a chance to hit the pool, you'll have a more accurate idea of whether your chlorine is holding or not. Keep brushing daily, and keep your filter running to get all the dead algae out.

Oh, and sorry about the gender mixup--somehow, in reading your username, it stuck in my mind as "Virginia". Sorry!! :o

Janet

Thanks for all the help!

This morning I tested the water and it appeared to be above 5 PPM. I didn't have time to dilute the sample but I was happy to see it high.

I came home today and took a sample and again it was reading 5 PPM. I was able to dilute the sample to 1/2 and it was between 2 and 3 PPM. I think the algea is dead as the sun was shining all day.

I have been brushing and couldn't understand why the algea kept coming back. After taking a few weeks of readings in the beginning of the season and having the same readings I do things automatically and was putting chlorine in at night assuming that it was lasting until the next day. I guess it's never too late to learn something!

Thanks again!

Vinny

PS: I really wasn't upset about the she thing.

You need to get your chlorine up to shock level, and hold it there for a couple of days or you will be fighting algae for the rest of the summer. You can tell the algae is gone if you hold Free Chlorine overnight. There should not be any combined chlorine. I would suggest you invest in a good test kit - one that can test over 5ppms of chlorine. It will be the one of the best investments you can make.:)

I would think that after adding the chlorine yesterday afternoon with the sun off the pool and having it in the sun all day today (7 AM to 3 PM) with low stabilizer (35 max) and getting a reading of 5 - the algea is pretty much gone (maybe not). If I remember correctly 10 PPM stabilizer is supposed to protect 1 PPM chlorine so 35 PPM would protect 3.5 PPM chlorine and the chlorine was over that.

I've been adding bleach since Saturday at high levels a few times a day and it hasn't dropped below 5. I don't have any visible signs of algea unlike other days. If algea is present wouldn't my chlorine would have been used up by now (see 1st paragraph) or at least showing low. My pool is not smelling like chlorine and when I tested for CC on Sat after putting chlorine in at night it didn't register any.

I am going to test the pool in the AM and see what the reading is and if it does drop below 5 I will add more chlorine, heck I'll just add more chlorine anyway.

Not much difference in a Taylor K-2005 and a Taylor K-2006, I can measure high levels of chlorine by halving the pool's water and multiplying the reading by 2 or if higher 1/3 and x3.

Please let me know if what I said makes sense.

Thanks!

I am going by Ben's "best guess chart". While the cya would protect 3.5 ppms of chlorine, it is not enough to kill all of the algae. The shock level for a cya of 35 would be 15ppms. My understanding of this chart is taking it up to 5 would not be enough to kill all the algae. It would keep it under control for a while, but not kill it all at one time will cause you trouble any time your chlorine is low. I know that when I start to have problems holding onto chlorine, I don't always have cc, or the smell of chlorine right away. I have found it easier to deal with it at the first sign by taking my chlorine up to shock and leaving it there until the chlorine holds overnight. In my opinion you are right on the border of controling the algae bloom. You have enough chlorine in the water to keep killing algae, just not enough to kill all of it.When I was battling my swamp in the beginning of the season, I didn't smell anything in my pool, but the chlorine was still being used up overnignt. It did use less and less as time went by, but it did take a while. I am only giving you my suggestions based on what I have experienced. It is up to you to do what you think is best.

Quote:

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Originally Posted by vinnygnj

Not much difference in a Taylor K-2005 and a Taylor K-2006, I can measure high levels of chlorine by halving the pool's water and multiplying the reading by 2 or if higher 1/3 and x3.

Please let me know if what I said makes sense.

Thanks!

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Actually, there is a HUGE difference in DPD and FAS-DPD testing. First, it has been found that about 4 out of 5 men have difficulty in differentiating the red colors on a DPD test (women do not have this problem) and second, dilution decreases your precision on the test so the FAS-DPD test is much more precise (down to .2 ppm!) compated to doing dilutions with the DPD test. The K-2005 does include dilution marks on the tester for 1:1 dilitions (multiply results by 2) and 1:4 dilutions (multiply results by 5) but these are only really going to give you more of a ballpark figure while the K-2006 will give you results that are precise to either .2 or .5 ppm depending on the size of your testing sample. (I have both kits, among others).

Also, FAS-DPD testing directly measures CC instead of measuring TC and then having to subtract the FC from the reading.

mbar,

I guess I actually didn't ask any questions, I was just thinking out loud. I don't have a very big outbreak of algea and luckily my pool didn't get away from me.

If my chlorine didn't disappear to 0 or very low, hasn't the algea been killed? When you were fighting the algea battle where you losing only a small amount of chlorine at night or most of it? I have fought with it and have had no chlorine by morning - that's why I ask.

Since the chlorine didn't go below 3 and my stabilizer is probably around 35, isn't all my chlorine above 3 killing anything it can? I put enough chlorine to last a night and a day of sunshine.

I know of 2 reasons for shocking a pool 1) breakpoint chlorination which I know isn't practiced here and 2) put enough chlorine into the water to kill the organisms and make sure there is enough chlorine left over so that you're assured a kill (and yes it might take days to accomplish that kill if chlorine gets too low). Why go to 15? Is there something else I'm missing?

waterbear,

I understand the color thing and yes at times I can't tell the difference between 1, 1.5 or 2. But I usually can tell the difference between 2, 3 and 5. Maybe other men can't and maybe as I get older I will lose this ability so I will have to go to the K-2006.

As far as the precision of the testing, why do you need to be that precise?

I know that that as CYA rises you need to add more chlorine but is there really a difference between 5 PPM and 5.5 PPM at a CYA of 30 or 100. I would think that if you were close to a important level that you just add more chlorine for a safe measure. If I almost halved the water and I almost got to a reading of 3, well I'm about 6 - I don't see a problem unless you wanted to precisely add enough chlorine for breakpoint chlorination but like I said - add more than just enough.

With CC, I thought that the only time you test it is when you lose large amounts of chlorine and you need to break the CC before it starts smelling? I was under the impression that the belief here is that sunlight destroys the CC. I typically don't test for CC in the pool after Ben stated that and whenever I have I had none.

Owww, my head hurts:confused: I will leave this to the chemistry pros, like waterbear and chemgeek. All I know is that whenever I lose chlorine overnight, it is because it is fighting something. If you lose a few ppms it is ok when the water starts at shock. I just think you are asking for trouble when you are playing around with such small numbers as 1ppm to 3ppms to do the work. Just as you said, it is not precise, therefore I would take it to shock and keep it there until the chlorine seems to be holding. You can tell with your own pool, as everyone's pool is different. So you can do as you like, but why are you so adverse about shocking the pool? If you are just after the reasons why shocking is needed, then I will leave it to the chemistry pros:D

Didn't mean to make your head hurt!

I like knowing the reasons to things.

Quote:

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Originally Posted by vinnygnj

Since the chlorine didn't go below 3 and my stabilizer is probably around 35, isn't all my chlorine above 3 killing anything it can? I put enough chlorine to last a night and a day of sunshine.
Algae is harder to kill than bacteria and 3 ppm FC is the MINIMUN for a CYA above 30 ppm (but less than 50 ppm). It often takes a higher level to keep algae at bay.
I know of 2 reasons for shocking a pool 1) breakpoint chlorination which I know isn't practiced here and 2) put enough chlorine into the water to kill the organisms and make sure there is enough chlorine left over so that you're assured a kill (and yes it might take days to accomplish that kill if chlorine gets too low). Why go to 15? Is there something else I'm missing?
I don't know why you have the impression that breakpoint chlorination is not practiced here. Breakpoint means adding enough chlorine to destroy any CC in the water. The formual for breakpoint (10x the CC level) does not always hold true and that is what is usually said but the actual process of reaching breakpoint is what is talked about when people are told to shock to destroy CC.
waterbear,

I understand the color thing and yes at times I can't tell the difference between 1, 1.5 or 2. But I usually can tell the difference between 2, 3 and 5. Maybe other men can't and maybe as I get older I will lose this ability so I will have to go to the K-2006.

As far as the precision of the testing, why do you need to be that precise?
Well, since it's usually recommened to 'shock' when the CC is greater than .5 ppm and you yourself said that you cannot differentiate tha small an increment with the DPD test I think that answers your question.
I know that that as CYA rises you need to add more chlorine but is there really a difference between 5 PPM and 5.5 PPM at a CYA of 30 or 100.
At a CYA of 100, no. At a CYA of 30, possibly.


With CC, I thought that the only time you test it is when you lose large amounts of chlorine and you need to break the CC before it starts smelling? I was under the impression that the belief here is that sunlight destroys the CC. I typically don't test for CC in the pool after Ben stated that and whenever I have I had none.

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According to the precision of your testing which you have stated is 1 ppm or greater!

I understand the concept of breakpoint chlorination, I could swear that I read a post by Ben a few years ago that he didn't beieve in the process of breakpoint chlorination, he made mention of CC will be broken down by sunlight - I guess I'm mistaken.

The K-2005 kit has an increment at 0.5 PPM and I can see that. I did check for CC when my chlorine was 0 and had none. I stopped checking my CC based on the above info. I do throw in 2x the normal chlorine at times to kill anything that hasn't been killed. I should have checked that my CYA was still there and probably should have shocked the heck out of the pool in the beginning of the season.

It definately is a learning experience.

The comparator in the K-2005 is calibrated at .5, 1, 1.5, 2, 3, and 5 so while it can determine .5 CC at lower chlorine levels it's precision is only 1 or 2 ppm at the levels most likely encounted in pools with normal CYA levels (3.5 ppm FC and 30-50 ppm CYA). Dilutions will further decrease the precision of the test. This is why FAS-DPD testing is better. The precision is either .5 ppm or .2 ppm (depending on sample size) no matter what the FC level is.

I wonder if this is the thread you are referring to when Ben said he wished people would not test CC? I think the point he was trying to make was that people worry too much about small amounts of CC spikes when they should be worrying about general water maintenance. UV will destroy these small amounts of CC but if there is a large amount caused by some chlorine demand then high chlorine levels are needed.

Here and Here are artricles by the PPOA about superchlorination which basically say the same thing Ben said in the thread above and have some veryi interesting info.

That probably is the post and I understand that small amounts need not be burned off with chlorine but I would also think that adding 6 PPM FC to a pool with 0.5 PPM CC will burn it off assuming that the CYA is at a low level.

As I said I never test for CC in the pool, only my spa but I guess in a situation like what I'm going through it might be worthwhile to test. But ...

... now more questions come to mind - Can CC really start accumilating if you are running high FC (8 - 10 PPM or more)? I would think not as anything under 1/10 of the chlorine you put in would be burned off (I am assuming that the pool started at 0 PPM CC and CYA is under 50). My pool was at 0 CC when I noticed I had no CYA.

How long do you need to keep a high chlorine environment? If you put in 10 PPM FC at 6 PM and you test at 6AM and have 6 PPM left, hasn't the chlorine done it's job. I always thought that as long as you have a FC residue that there isn't any more that the chlorine needs to do. (again CYA under 50). And wasn't the high chlorine in the tub burning off the CC as it was forming?

In my mind, a "shock" really isn't a specific quantity - it can be as low as 5 PPM FC or as high as 20 PPM FC, which is why I questioned the 15 FC figure for shock.

At this point with my pool not seeing a FC under 5 PPM since I started this post I would assume that any algea is dead. I actually put in 146 oz of bleach into my pool last night which yeilded 7 PPM chlorine added to what was there I was hovering around 11 to 13 PPM. I "shocked" the pool for the last time although I doubt there was a lot of CC in there.

CC can accumulate, it depends on how much ammonia and urea or other organics are in the water. If you are killing algae then 0 ppm CC is a good indicator (along with the Fc holding overnight) that you have killed all the algae. If you do not raise the FC high enough to destroy all the orgainics in the water you will still have CC left.

Your example of putting in 10 ppm FC at 6 pm and losing 4 ppm overnight indicates that the chlorine is fighting something in the water and you need to continue to shock until the FC holds overnight when UV degredation of chlorine is taken out of the equation. This is a basic of the BBB method on here. Just read the posts!

"Shock" is really raising the FC high enough for the level of CYA in the water to insure that there is enough 'active' chlorine to do the job and it is not bound up with the stabilizer in the form of chlorinated isocyanurates but is in the form of hypochorous acid.

It is a combination of having no CC and having your FC levels hold that indicates that you do not have a chlorine demand in your pool. If this is not the case you need to continue shocking and possibly try shocking to a higher FC level. It is also important to keep the FC at shock level by adding more chlorine at least a few times a day.