Calcium Hardness at Zero

[Lenny]

Hi All,

I haven't used my pool much in the past month (just used the spa once). I'm just getting ready to close it for winter. The cover has been on for a month or so.

The last time I tested calcium hardness was Sept. 28th and it measured 260. Today I am testing it and the reading is zero! I have a couple different bottles of the first reagent you are supposed to use (which would cause a red color) and they are both showing the same thing. I also sampled water from a few different areas of the pool and let things circulate for a while but nothing changed.

My free chlorine is 8, alk. is 110 and PH is 7.9. I was running my filter and SWG some each day just to move things around because some nights have been below freezing.


Any ideas what might be causing this? The water is cold but I've tested it this cold before and did not have this problem.

Thanks.

 

[JasonLion]

Ch levels don't just go down to zero by themselves, so I figure something must be wrong with the test. Could you describe what you see when you do the test, you add the drops and the water does what, turns what color in what order?

 

[Lenny]

Thanks for the reply, Jason.

I'm using a Taylor test kit and the problem is when I put the first 20 drops in of reagent R-0010 the normal red color isn't there. It's totally clear.

I'm going to pick up some new reagents and try this again. I had 2 bottles of R-0010 and it would be surprising for both of them to be bad but you never know.

It is hard to conceive how CH could suddenly be zero so hopefully and the fact that nobody has chimed in here with some kind of explanation as to how this could happen probably tells me what I need to know .

Thanks,
Lenny

 

[CaOCl2]

I'm using a Taylor test kit and the problem is when I put the first 20 drops in of reagent R-0010 the normal red color isn't there. It's totally clear.

The R-0010 increases the pH of the sample. You then need to add your 5 drops of R-0011L after which the water should change color. Proceed with the titration by adding R-0012 dropwise until the color change is permanent.

 

[JasonLion]

On the standard Taylor CH test you add 20 drops of R-0010 and mix (the water is still clear at this point), then you add five drops of R-0011L and mix and the water turns red, then you add one drop of R-0012 at a time till it turns blue. From your description it sounds like you left out the R-0011L.

There is another version of the test where you add R-0854 first and it turns red right off, but you said you started with R-0010 which would mean you don't have that version of the test.

 

[Lenny]

That's right. I recall now that it was the R-0011L that turns it red normally.

Well, I bought new reagents and the test went fine. False alarm! I should have known better.

Thanks for your help.