Testing for high chlorine levels

[PoolDoc]

My kit uses two tiny tubes with colored patches corresponding to chlorine levels and pH.

You probably have the K-2005, which Leslies's sells. The problem is (a) the red shade is one a lot of people have trouble with, (b) the range only goes to 5 ppm -- some kits 'read' higher, but people don't, & (c) DPD color match reads 0 ppm for levels that are 0.0 ppm FC *and* for levels that are 15 ppm FC!

You need the K-1515.

Phenol red color match is sufficient for the task, unless you are color blind. Acid and base demand can be used to quantify pH levels outside the measurable range.

This is not very precise; a better way would be to use a proper indicator and count the number of drops and then convert to chlorine or pH.

It would be more precise, but would not necessarily be better. More precise is ONLY better when you NEED more precision; otherwise, more precision is just a PITA.

I constantly have to fight some people's tendency to try to run a set of numbers, instead of a pool!

As I remember my qualitative and quantitative analysis college chemistry courses many years ago this would be "easy" for pH; I have no ready idea what indicator would work for chlorine.

As it happens, the acid / base demand test in the K2005/6 -- if that is what you have -- operates as close to that as you will get with pH. If you want ACCURATE pH results, you need a double buffer calibrated pH meter. But, the only people that normally NEED such a meter are those with color perception probelms.

Also, in the K-2005/6, both the alkalinity and calcium hardness tests are straightforward titrations with an indicator (methyl orange; Calcon): the only difference is you are using a dropper tip instead of a titration and a tube instead of a flask.

In the K-2006 -- and this is the critical difference -- the chlorine test is ALSO a back-titration, with "FAS" -- ferric ammonium sulfate -- to a 0.0 ppm FC level

If I dilute the pool water with an equal amount of distilled water (to avoid any domestic supply chlorine) and then test for chlorine levels, wouldn't the indicated levels with the test kit represent 1/2 of the chlorine levels of the undiluted sample? So an indicated 5ppm via the kit would actually be 10ppm?

That process is described in the "How to test without a good testkit" sticky.

[George in GA]

Sorry to have bothered.

[PoolDoc]

I'm sorry for being 'testy'; it's been a very long week, and I'm about used up. Newbies are newbies, educated or not, and I know that. God knows I've done enough of that myself!

But it takes a bit of self-control -- never one of my strengths -- to avoid snapping at people who ask unnecessary questions, like yours. As in every area of life, solving problems is maybe 20% technical and 80% people, and I know that too.

There's not much for me to take back; everything I told you is both true and relevant, and if there's a way to 'take back' having said it badly, I've never discovered it! Again, as God knows, it's something I could have used many, many times.

So, yes, you 'bothered' me, and yes, your questions were unnecessary to the function of your pool. But it's part of the learning process, and I responded badly. I hope you'll forgive me.

[CarlD]

Just to simplify: If you have the Leslies equivalent of the K-2005 (and, yes, Leslies sells it--it's actually a Taylor re-badged) then all you need is the Taylor K-1515 to "convert" the K2005 to the recommended K-2006. You use the FAS-DPD chlorine test instead of the DPD Chlorine test.

You CAN use the "Patented (j/k) CarlD Shot Glass Method" with an OTO tester like you have to double, triple or even quadruple the reading, using distilled water as you did. However, if you search the forum, you'll find Ben posted another way to use the OTO kit to measure without dilution, with reflecting what it means when the test goes deeper yellow, orange, deep orange, then brown ( I think brown is around 40? ppm?) But you don't get the FC and CC reading, only TC.

BTW, Leslies also sells a re-branded version of the Taylor K-2006 kit.

Carl

[George in GA]

Apology accepted.

As one who has taught and as a retired librarian I can well understand the fatigue of fielding the same question over and over and.... I often had to tell myself that the d*** fool question wasn't unnecessary to the seeker.

The main reason I asked the question, BTW, was to fulfill the posting requirement of the site. Perhaps I just should have said "Hello."