Unable to maintain chlorine levels

I have never had the problem I have now and it is very frustrating.

Every day when I check the chlorine level it is on zero. I keep my automatic feeder full and turned all the way up and I have started placing 3 tablets in the skimmer. (I have a 20,000 gal pool). I have been shocking it about 2-3 times a week in an effort to get the levels up (using about 4 pounds of trichlor). On the evenings I shock, the next am level is still zero. My stabilizer level is normal. This is becoming more expensive as I am running through my shock. What in the world is going on?

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Originally Posted by medstudy

I have never had the problem I have now and it is very frustrating.

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You are in the right place.:)

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Every day when I check the chlorine level it is on zero.

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How are you testing? (i.e. test stips, 5 way kit with drops etc.)

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I keep my automatic feeder full and turned all the way up and I have started placing 3 tablets in the skimmer.

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So, you are using both an automatic feeder AND putting pucks in the skimmer? This is probably way to much.

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(I have a 20,000 gal pool). I have been shocking it about 2-3 times a week in an effort to get the levels up (using about 4 pounds of trichlor). On the evenings I shock, the next am level is still zero.

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Something is obviously chewing up the chlorine. It could be Algae, chlorine, phosphates, ammonia, the sun or a host of other possibilities as well as the possibilty that you have a lot of chlorine and it is bleaching out your test.

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My stabilizer level is normal. This is becoming more expensive as I am running through my shock. What in the world is going on?

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What is "normal"? First thing you should do is post some numbers for FC (free chlorine) CC (combined chlorine) PH, ALK (alkalinity) CYA (aka stabilizer or Cyanuric acid). These numbers should come from a drop based test kit or your local pool store. If you go to the pool store, don't let them sell you ANYTHING! The people here can help you for a lot less money and a LOT less time. Post your numbers, don't add anything else and tell us what all you have added to the pool when posting (i.e. dichlor shock, algaecide {brand/type}, clarifier etc.) Also tell us what type of pool you hace ( gunite, vinyl or fiberglass etc.)
Again, if you are tired of throwing money at your pool to no avail, you have come to the right place. I assure you, if you follow the procedures recommended here, your water will be safer and clearer than you have ever had.

Dave

I used an over the counter drop tester (OTO). I also had my levels checked at 3 different pool stores. I have a gunite pool
Here is a summary of the latest numbers.

Temp:80
Saturation Index: 0.4
TDS: 850
CYA: 50
Tot. Chlorine: 0.4
Free Chlorine: 0.4
pH: 7.7
Tot. Alkalinity: 139
Adj. Total Alk: 124
Tot Hardness: 314

Since these numbers, I have added pH decreaser to normalize the pH. I have also added 4 lbs of trichlor yesterday, but the current chlorine level is around zero.
I thought about your idea that high chlorine may be bleaching out the test, but when I check the chlorine levels about 30min after the shock, it tests in the high range as you would expect ( dark yellow) (greater than 5.0 which is the limit on my tester). It is on the following day that the chlorine levels go to near zero. I wonder if I have an algae bloom somewhere in the piping of filter than I cannot see, although the water is clear. Thank you for the help.

Before everyone jumps on the "your chlorine level is too low for the cya level you're maintaining", my two cents worth of advice is this:
You have a high chlorine demand SOMEWHERE, and the only way to get rid of this is to satisfy the demand. This means continually adding chlorine to maintain a high residual until you see the residual maintaining. With cya in your pool, you should be able to maintain the residual for 2-3 days before it dropping off.
I'd recommend using just regular bleach to add EVERYDAY until corrected.
Check your filter to make sure you're not harboring algae in there.

Have you needed to add any chemicals for algae? Most sodium bromide based algaecides require that you add an oxidizer (some form of chlorine) to activate it, and to repeat the dosage several days later. This can affect your chlorine tests.

With salt generators, I recommend maintaining 5-7 ppm (you can go higher if you want) with the system turned off, for a week or two, whenever sodium bromide is used in a salt generator pool.

I like the idea of bleach, sounds cheap. How do I add bleach? Any particular kind? How much?

medstudy,
Welcome to the forum.
You are in the right place to learn about bleach, borax, and baking soda and how to maintain your pool without breaking the bank! (and having the best water in the neighborhood). I am totally serious about this! I would suggest you go to the sister website of this forum www.poolsolutions.com and read EVERYTHING on it that you can (some sections are subscriber only), then come back here and and read the FAQs and stickies at the top of each forum subheading. You will then have a good idea on the BBB method of pool care. Anything you don't understand just ask...there are plenty of members here who can guide you!
BTW, I know you posted the same question in another forum. I answered you there. IMHO, THIS forum is the place you will find the answers you are looking for without the misinformation so prevalent in the pool industry!

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Originally Posted by medstudy

I used an over the counter drop tester (OTO). I also had my levels checked at 3 different pool stores. I have a gunite pool
Here is a summary of the latest numbers.

Temp:80
Saturation Index: 0.4
Bogus measurement
TDS: 850
another bogus measurement
CYA: 50
within the recommended range but won't stay there long if you continue to use trichlor!
Tot. Chlorine: 0.4
Free Chlorine: 0.4
As Poolsean said, you have a huge chlorine demand happeining! You need chlorine until the demand is satified and the chlorine is holding. Unstabilized chlorine would be best. Bleach is unstabilized chlorine.
pH: 7.7
Would leave this alone now until the chlorine demand is met.
Tot. Alkalinity: 139
Adj. Total Alk: 124
Tot Hardness: 314
I wouldn't lose any sleep over these numbers.
Since these numbers, I have added pH decreaser to normalize the pH.
Muriatic acid is more effective and less expensive (but not as nice to work with). ..most of us on here use muriatic acid but either one is fine.
I have also added 4 lbs of trichlor yesterday, but the current chlorine level is around zero.
I thought about your idea that high chlorine may be bleaching out the test, but when I check the chlorine levels about 30min after the shock, it tests in the high range as you would expect ( dark yellow) (greater than 5.0 which is the limit on my tester). It is on the following day that the chlorine levels go to near zero. I wonder if I have an algae bloom somewhere in the piping of filter than I cannot see, although the water is clear. Thank you for the help.

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Your chlorine demand might be coming from some other source than algae. I am curious what kind of filter you have and what condition the filter medium is in. Also, have you added any chlorine 'enchancers' or sodium bromide algecides to the water? Both of these can create a hugh chlorine demand. Fertializer washing into the pool can create a chlorine demand. Bottom line, it doesn't matter where it comes from...you just need to keep adding unstabilized chlorine, perhaps 3 times a day, to a level of at least 12 ppm until it is met.

I would also suggest that you get a good drop based test kit that uses the FAS-DPD titration test for chlorine (this will allow you to test high free chlorine levels accurately as well as small levels of CC), along with tests for pH, ALK, Calcium Hardness, and CYA. That way you can take control of your water. The Taylor K-2006 is a good choice but a better 'bang for your buck' is the ps234 kit sold by the administrator of this forum on the PoolSolutions website! I have one, as do many of the forum members, and it really is the best kit out there and the best value for the money!

Thank you for all your help so far. You are right, I am posting on 2 forums. I posted them at the same time because I did not know which forum is better since I have not even been to a pool forum until I started having this problem.

I have a Hayward sand filter. I dont know how old it is, because we just moved in the house, but my guess is that it is about five years old. It appears to be in good shape, however I do have a concern about it; I notice trace amounts of sand in the "view glass" during backwashing and I notice that my polaris is picking up very small amounts of sand. This makes me wonder if I have a sand "leak" and if so, if that contributes to my problem. My piping is fixed to the filter so it looks like it would take some sawing to get the filter apart to look in.

I did add some algaecide to the pool a few weeks ago. It was the over the counter Aqua Chem stuff that you buy at Wal Mart. Can that do it?

Medstudy,

You seem to be bypassing the advice to put chlorine in your pool. Is there a reason for that? Is your water still clear?

Nevertheless, I would suggest you raise your Cl in the evening to 30ppm. Then retest the next morning. If you have lost more than around 2-3ppm, you have lost it to organics in the pool and you must keep killing them.

Bring it back up to around 25-30 each evening 'til your Cl holds overnight and then let it drift down into 4-8ppm range. That cure the issue. To do this correctly you will need a test kit that tests Cl for levels that high and accurate calculations and dosage to obtain the proper level.

I put 8 lbs of shock today. I checked the level about 2 hours later and it was >5.0ppm so Iam hoping I am there. I will let you know tomorrow. The water continues to be clear, I think because I am being active at putting the shock in.

This morning the chlorine level was undetectable. I went to the Wal-Mart and bought 10 one gallon jugs of the generic bleach which is 6% sodium hypochlorite. I put in 6 gallons. We will see what happens!:confused:

That should bring you up to 18 ppm chlorine....check your chlorine levels througout the day and if they drop add more bleach. You have to keep doing this until the chlorine is holding...it might take a lot of bleach.

Just an update. I put 6 gallons of the 6%bleach in this am at about 10am. I rechecked the levels at 3pm and they were down to zero. I only had 4 gallons left so I put it in. It sounds like I am going to have to make another dash to the Wal-Mart

Keep it up and you will find that you solve the problem!

Well, I am still keeping up the fight, but now a new problem.

I am leaving to go out of town for 7 days and I still don't have a stable concentration yet. ( I put in another 6 gallons today). What would you guys do? I have an automatic cover (saftey cover) for the pool. I was thinking about just covering it for the 7 days and leaving it alone. I just can't afford a pool man yet and we don't know any of our neighbors yet (we just moved in).:confused:

What are your stabilizer and pH levels? If the pH is too high and the stabilizer is too low, you're going to go through alot of chlorine. What is your combined chlorine level? What are your Total Alkalinity and Calcium Hardness?
How many hours per day is your pump running?

You're best to take a water sample and have it tested (or test it yourself) and report the results back here. We can advise better with this information.

If these are within proper levels, you may want to ....gulp...get a cheap chlorine tablet floater and let it float in the pool, but make sure your pump is running the whole time. This will add chlorine, stabilizer and drop the pH slightly while you're gone. It's a better option than letting the pool turn green.