how much chlorine?

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O

opaz

Member
Jun 27, 2019
12
Brit in France
Hi, I inherited a pool which was in a terrible state - more like a pond (approx 100,000 m3). I've cleared all the rubbish out, vacuum brushed the floor to remove the dark patches (got rid of most of it, a few tiny patches remaining).

I've added 3x 20 litres 9% bleach solution but it was just turning it blue for a couple of hours, then back to green. So I added 20 litres of 12% chlorine which seems to have kept it blue, which is encouraging.

After about 24 hours I tested the water got this:

Free chlorine = 0
Alkalinity = >40
pH = 7.2
CYA = 25

I added my final 20 litres of of 12% chlorine this morning. I tested it again after about 12 hours and the results are pretty similar - zero free chlorine (pH still good, CYA is down)

So.... do I just keep adding more chlorine until I get up to 1-3 ppm? If so, how much?

Thanks in advance
 
Welcome to the forum!
From other members in your area, test kits are hard to come by. I suspect you are using test strips for your data?
You need to SLAM Process. Tough part is you need keep FC at 12 ppm IF your CYA is really 25ppm. I doubt you can test FC that high.
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
 
Any chance you can obtain the Taylor K-2006 test kit over there? Online perhaps? What pool test kits do you have available to you?

After you put the chlorine in, do you re-test sooner than 12 hours later to see how high your FC has gone? Do you have any way of testing for Combined Chloramines?

Maddie :flower:
 
Nope - I'm stuck with paper test strips at the moment. Presume I can get a proper kit of Amazon though.

I went to the pool shop to get some more liquid chlorine and the lady insisted that what I should use is 'chlore choc' tablets. So I got some of those and dropped them in the skimmers. 2 days later the free chlorine level is up to 3-4 ppm which is encouraging.

So I'm wondering should I keep upping the dose of tablets till I get to the magic number - 12 ppm - or is this not possible with tablets and I should also add another big dose of liquid chlorine?

Might be an impossible question to answer. The complexity of pool chemistry is beginning to dawn on me. But I'm not looking to become an expert - just to pursue a logical strategy. My concern is - I don't want to just keep adding more and more chlorine if there's a danger of screwing up the pool chemistry in a way I didn't anticipate
 
The problem with "chlore choc" tablets is that they probably also contain CYA stabilizer. As that goes up in your pool, so too must the FC. Yet it becomes a vicious circle if you try to again use them to get the FC up....

Liquid chlorine does not contain anything like stabilizer or calcium.... it simply breaks down to water and a little salt left behind.

Try to get a good kit on Amazon. It needs to contain the FAS-DPD chlorine test.

In the mean time read our pool school articles as Marty suggests--> ABCs of Pool Water Chemistry
www.troublefreepool.com

Recommended Pool Chemicals

Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.
www.troublefreepool.com www.troublefreepool.com

Maddie :flower:
 
We just can't offer advice based on test strips. They have proven to be unreliable. How can you know if you really have 0 chlorine or if it is so high the pads have been bleached out?

Stick with the liquid chlorine, add 5ppm each day until you have a drop based test kit, ideally the FAS-DPD, a far 2nd place would be the yellow OTO test.
 

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