How much Chlorine is too much?

[Dave S.]

Great advice, and thank you for the calculations!
My testing kit only goes up to 5ppm for cl.

I can't find any kits locally that will go higher. How can I safely stay within the range?

[aylad]

In a pool your size, know that 1/2 gallon of 6% bleach will raise your Cl by 1 ppm, so if you know your starting point, you can calculate what it will be based on what you add.

In the meantime, to get a ballpark estimate of your current chlorine, you can use CarlD's patented "shotglass method", which consists of mixing one part pool water with 1 part of distilled (non-chlorinated) water. Mix well, run your test, then just multiply your result x 2. If that's still not high enough, you can mix it 1:2 and multiply result x 3, etc. Each time you dilute it you're losing a little accuracy, but it'll give you a good ballpark estimate, and there's enough leeway that even if you overshoot by a little due to the dilutions, you still won't damage your liner.

Janet

[CarlD]

Aha! Do a search within PoolForum for the Shot Glass method! You'll need a bottle of steam distilled water, which your local grocery or discount drug store has.

The idea is you dilute pool water and then measure the chlorine in it. So...if your kit goes to 5 (and I assume it's an OTO kit with yellow reagent), then if you mix a shot glass of pool water with a shot glass of distilled water, when you measure it, when it reads "5" on the tester it's actually 10ppm! Mix 2 shots of distilled to one of pool and it as if the scale goes to 15ppm!

Got it?

[aylad]

Beat ya to it!!!

J

[CarlD]

Beat ya to it!!!

J

Dang!

[Watermom]

With CYA of 30, chlorine of 15ppm should be fine. If you look in the chart above, cya of 30-50 we suggest 15. But, since you are in the lower end of that range and a little unsure about taking chlorine up to 15, why don't you try taking it up to 12 and keeping it there consistently for a few days. That may be high enough to take care of things. If you find that it isn't, you can always bump it up to 15 in a day or two if necessary.

[Dave S.]

With CYA of 30, chlorine of 15ppm should be fine. If you look in the chart above, cya of 30-50 we suggest 15. But, since you are in the lower end of that range and a little unsure about taking chlorine up to 15, why don't you try taking it up to 12 and keeping it there consistently. That may be high enough to take care of things. If you find that it isn't, you can always bump it up to 15 in a day or two if necessary.

Will do. Thanks!!

[Dave S.]

Okay, so I went ahead and shocked the heck out of it. Added 6 gallons of 10% chlorine...
4 hours later (or so), the pool is blue. Cloudy, but very blue. Not a trace of algae left.

Now, I just have to be patient while the filter does its job and clears up the water.

Thank you for all of your help!!

Dave

[Watermom]

Although it loses accuracy, you can use dilution to get a ballpark figure when you need to test higher chlorine levels than your kit can normally register.

Take one part pool water and mix it with one part distilled water. Then, fill your tester with some of this mixture and test as usual and multiply your results by 2. If that doesn't go high enough to help, mix one part pool water with 2 parts distilled and then multiply results by 3, etc. You do lose accuracy with each dilution so it is not ideal, but better than nothing. What you need to do is to go ahead and get a good test kit like the Taylor K-2006 so you'll have it.

[Watermom]

Geez -- We must have all been typing at the same time --- all three of us posted within 3 minutes of each other. How's that for service having three of the moderators do that for ya!!