free chlorine and total chlorine problems

[mnvanci]

Hi I have a problem with cloudy water. My winter cover blew in during a terrible storm last week with basically everything going into the pool (all that junk and water). I have a 14,000 gallon pool. My readings are as followed.
CYA 50
total Chlorine 8
Free chlorine 0
ph of 7.4
alkalinity 170
total dissolved solids of 850.

I have added phosfree because my phosphates were at 1000. Now they are down to 200.
What can I do to get my free chlorine off ZERO!!! HELP! I have already shocked to pool with 4 bags of shock and 2 liquid gallons of shock.
Thanks,
Mark

 

[frustratedpoolmom]

Hi Mark. Have you read Pool School? Start with How to Shock your pool. I'm guessing you just aren't shocking properly.

 

[mnvanci]

I have never had a problem until this year with the cover blowing in. Why is the free chlorine at 0 while the total chlorine at 8?

 

[JasonLion]

PHOSfree won't help at all. It has nothing to do with this.

High CC levels that stay about the same despite adding huge amounts of chlorine are the result of a fair bit of ammonia getting into the pool. That can come from fertilizer getting into the pool, or CYA breaking down over the winter, or someone pouring a bottle of ammonia into the water.

There are only two possible solutions. Nearly all the time the best solution is to just keep adding chlorine until the CC is finally all gone. The second option, if the ammonia level is really really high, is to replace water to get the ammonia level down. If you are worried about it you can get an ammonia measurement or do an extreme chlorine demand test to see approximately how much chlorine you are going to need to use.

 

[mnvanci]

So should I keep adding liquid chlorine? How much chlorine and is cc ammonia? Thank you so much for your help. I am worried about it.

 

[JasonLion]

Yes, I recommend that you continue to add chlorine at least once a day.

If you are concerned about how much chlorine you need, you can follow the procedure in this post to get an estimate of how much total chlorine you are going to need.

 

[mnvanci]

Ok - does this sound correct. After doing this test and some math. I figured I need to buy 21 gallons of liquid chlorine. Does this sound correct or is my math wrong?

 

[JasonLion]

You didn't tell us what the result of your chlorine demand test was, so we can't check your math.

 

[mnvanci]

Ok I did this.
Put five gallons of pool water in a bucket.
2) Add 1 oz of 6% bleach
3) mix throughly
4) wait one hour
5) test the FC level
6) The fc is above 10

 

[JasonLion]

Good, it took less that 86 ppm of chlorine to clear up the water. We don't know exactly how much less, but that puts an upper bound on how much chlorine you will need to use.

I suggest you add about three large jugs of bleach (a little over 4 gallons), give it an hour to mix in, test the FC level, and as long as FC is below 10, repeat. If your test was done correctly, you will need to do that somewhere between once and five times.

 

[mnvanci]

Thank you so much for your help! You are the best! Tomorrow night is a shock party at my house!!

 

[mnvanci]

Hi jasonlion,
The pool store said it could clear up on it's own. That the combined chlorine will lower naturally and I don't need to shock. They said that with the cold water and sunshine it will go down. I am not sure to believe them. What do you think?

 

[duraleigh]

Is that the same poolstore that told you to use phosphate remover?

 

[JasonLion]

Their advice really make no sense in the situation. While normal levels of chlorine plus sunlight will break down CC, you can't maintain normal FC levels. Even if you could maintain an FC level, you have enough ammonia in the water that breaking it all down that way would take months. Meanwhile, you wouldn't be able to swim because you can't maintain an FC level.

 

[mnvanci]

I don't trust them. My pool is cloudy and the did tell me to use the phosphate remover. They don't seem to know what they are doing. I am planning on shocking tonight. Thanks for your advice, I really appreciate all of your help. You are the best!

 

[chem geek]

The bacterial conversion of CYA into ammonia when the chlorine levels gets to near zero is something that can happen to anyone if they don't maintain the proper chlorine level at all times. It happened to me and you can see a log of my readings and how much chlorine it took in this post. Note that it took frequent additions of chlorine multiple times during the day before I started to get an FC reading and then it took time for the water to clear and for the FC to hold (decline at normal levels -- note that I have a mostly opaque electric pool cover).

 

[mnvanci]

I finally reached fc of over 10!!! So I am done correct ?

 

[frustratedpoolmom]

You are done shocking when:
Your FC Holds Overnight or you lose 1ppm or less;
Your CC is .5 or less;
Your water is clear.
All three criteria must be met before being "done".

 

[mnvanci]

Ok - Well my FC did not hold over night. My water is now clear. I have to test my cc. So do I keep shocking tonight. What do you reccommend as the strongest possible shock?

 

[JasonLion]

Chlorine is chlorine, it doesn't matter to the CC level where it comes from. The main issue when selecting a source of chlorine is the other things it adds to the water. Dichlor adds a lot of CYA, which often causes problems. Cal-hypo adds calcium, which is occasionally a problem. Generally bleach/liquid chlorine is the best to use because it doesn't add anything you don't want.