Innefective bleach?

[jjoshua]

I opened my pool on Saturday and it didn't take long to get everything balanced nicely:

FC 4
CC 0
PH 7.5
TA 90
CH 260
CYA 45

Then, last night, I added 60oz of clorox which was the correct amount to keep my pool balanced all last summer.

This afternoon, I was down to 3 FC.

I'm using bleach that was left over since last fall and was stored in my garage. This is the same bleach that I used to open the pool.

Is it possible that the bleach is not working at full strength or could there be something wrong with the water that would require me to shock?

 

[duraleigh]

Then, last night, I added 60oz of clorox which was the correct amount to keep my pool balanced all last summer.

That's a little confusing....60 oz of bleach will raise your FC by 2ppm in that pool. What were you expecting it to be?

 

[Richard320]

If anything, I'd say chlorine loss is kinda low...

 

[JasonLion]

Chlorine gets consumed every day and needs to be constantly replenished.

You can use the Pool Calculator to figure out quantities.

 

[jjoshua]

Chlorine gets consumed every day and needs to be constantly replenished.

You can use the Pool Calculator to figure out quantities.

I know that.

Last season, I would use 1/3 of a 182oz jug each night. That would keep my FC constant. This worked for the entire season.

This season, it's not.

Is it the old bleach or could it be something else?

 

[duraleigh]

You would have to do an OCLT to determine if it was something else....it could be either.

 

[jjoshua]

I'll give that a try.

 

[JasonLion]

Bleach does lose strength, especially if it is stored somewhere warm. If it is 6% bleach it shouldn't have lost too much strength. But stronger bleach would have lost a significant amount of strength.

Most likely you just need some extra chlorine to startup and won't continue to need extra bleach, but loss of strength is also possible especially if it was stronger than 6%.

 

[jjoshua]

I'm going to shock the pool because I won't be using it until next weekend at the earliest.

The sun is down and FC is 20. We'll do another test in the morning.

Thanks.

 

[jjoshua]

Overnight FC loss was negligible if any.

My startup went extremely well this year so I was expecting to get right on the same schedule as last year. If extra chlorine is required at startup to get everything going, then that would be a reasonable explanation.

I'll test every night to figure out my daily consumption and adjust the amount of bleach that I use if necessary.

Thanks.

 

[jjoshua]

Large FC drop during the day

Here's my current test results:

FC 11
TC 11
PH 7.5
TA 90
CH 260
CYA 45

Last night, I shocked the pool to FC=20. This morning, I had FC=20. OCLT good.

During the day, I seem to have lost a lot of FC. What's going on?

Should I add more CYA? I think that I have another 2 lbs in a bucket which would bring it up to 60.

 

[duraleigh]

Please keep similar posts in one thread so people can see you whole "story" It is confusing to everyone to start another thread.

 

[JasonLion]

That all seems completely normal. With CYA roughly around 50 you should lose roughly 50% of your starting FC level over the course of a sunny day.

 

[jjoshua]

So, at some point it will level off? I would expect to see it at 8 tomorrow evening?

I'm wondering if I should bump my CYA up to 60 or 80 to minimize FC loss. I understand that I need to maintain a higher FC but that doesn't seem like a problem.

 

[Isaac-1]

Like others have said, bleach looses strength with age, I recently had a couple of cases of "12%" that were weak, looking at the packaging I found they had a pack date in 2008.

 

[jjoshua]

FC is 5 this evening. I added 60oz of bleach and I'll measure tomorrow evening.

I'm going to see if I can maintain my pool like last year. If my FC usage is more than 60oz per day, then I'm going to increase my CYA a bit to slow down consumption. I don't mind maintaining a higher FC level if my usage is going to decrease.

 

[jjoshua]

FC is 5 again this evening. I'm going to up the CYA to 60 and try to maintain a 6-8 FC.

That should work nicely.

 

[Bama Rambler]

Re: Ineffective bleach?

So it was at 5 ppm and you added 60 oz of bleach or a little less than 2 ppm. And you measured 5 ppm again the next evening. So you're losing a little less than 2 ppm per day. I don't think you're going to get much better than that.