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Calcium Hardness Testing


egclassic

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Today I bought the (Taylor)reagents to test for CH.

I filled my vial to the 25mL line and added 20 drops of r-0010, and then 5 drops of 11L.

The sample turned pink for a second or 2 and then went clear.

Does this indicate that my Calcium levels are too high and that I should do the 10mL sample test?

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I don't know what that means and someone else had that happen to them as well. By any chance, is your chlorine level exceptionally high? What disinfectant are you using -- chlorine or bromine? Or is there any other strong oxidizer in the water such as non-chlorine shock (MPS) or using a very powerful ozonator?

If the problem is due to high magnesium levels, then you can start by adding titrant drops, say 10 of them, before you add the 20 drops of calcium buffer and 5 drops of R-0010, but be sure to count these 10 drops in your total titrant drop count. Another thing you can try is to add more R-0010, say 8 drops, since as an indicator dye having more of it isn't a quantitative problem.

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Thanks for replying.

I am using Bromine and the levels have consistantly been around 2-4. My pH seems to stay @ 7.5 with TA of 70-80.

I am guessing that I had a high CH, because I tried the 10mL test and the color held. My CH seemed to be 400.

This morning I drained about 1/3 of the water and refilled. My CH is 275 now. I do not use MPS as I think I had an allergic reaction to it, I use 6% bleach as suggested here, only when needed.

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Did you scale down the reagent additions when using the 10 ml sample size? The instructions say to add 10 drops of R-0010 instead of 20, 3 drops of R-0011L instead of 5, and count each drop of R-0012 as 25 ppm instead of 10 ppm. So their using 25% higher concentrations of calcium buffer and 50% higher concentration of indicator dye. Perhaps that is enough to overcome the side effects of high CH if that's what it is (or perhaps high Mg that the calcium buffer is handling). Thanks for the tip.

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Yes, I followed Taylors instructions for suspected high Calcium levels.(I may have added 1 additional drop of 11L)

I also tested my city tap water and I have approx. 200 ppm CH. I think I realized how my level got to 400 (maybe). I got this hot tub from a freind who lives in an area that has horribly hard water. If fact, every year, I go to his house to do a preventative maintenance on his electric water heater for this reason. One year, we skipped it, and the next year, I almost could not get the bottom element out of the heater. I kid you not, we always fill a 5 gallon shop vac with calcium deposits. Back to the point, He had this tub for about 4 years and I am suspecting that the plumbing in the tub has calcium build up in it, which may be leeching out into the water. Does this sound feesable? This spring I plan to replace the heater element and hopefully between now and then, I can come up with a plan to "flush" this build up out. I carry a product on my work truck called "Calci-solve" ( http://www.nucalgon.com/products/plumbing_calcisolve.htm ) which eats calcium and scale, but I fear it could damage my tub.

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Yes, calcium carbonate scale can redissolve if the water chemistry has some combination of low pH, TA and CH (especially low pH).

The pool products that help to dissolve or dislodge calcium are not harmful. They are usually metal sequestrants and sometimes an organic acid. If you were to use a strong acid and lowered the pH too much, then that would be of concern. The Calci-solve MSDS says it is hydrochloric acid, but says it has other inhibitors that protect pipes -- probably chemicals that slow down metal corrosion. It doesn't look like it was designed for pool/spa use, but the copper heat exchanger is similar to other copper plumbing. You might test the pH in the spa water to see how low it goes. If it's not for very long (hours, not days), it should be OK.

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Yes, calcium carbonate scale can redissolve if the water chemistry has some combination of low pH, TA and CH (especially low pH).

The pool products that help to dissolve or dislodge calcium are not harmful. They are usually metal sequestrants and sometimes an organic acid. If you were to use a strong acid and lowered the pH too much, then that would be of concern. The Calci-solve MSDS says it is hydrochloric acid, but says it has other inhibitors that protect pipes -- probably chemicals that slow down metal corrosion. It doesn't look like it was designed for pool/spa use, but the copper heat exchanger is similar to other copper plumbing. You might test the pH in the spa water to see how low it goes. If it's not for very long (hours, not days), it should be OK.

I was only planning on using it the next time I do a refill, and only during the last hour or so before draining. Calci-solve works pretty quickly, I use it about 2-3 times a week at work. It it safe for rubbers, plastics, steel, brass etc, but it will react with aluminum. I do know that the fumes will burn the chrome off of plumbing fixtures.

I may do an experiment to see its effect on pH before using it. Thanks!

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So if you have copper piping in the heat exchanger, it'll probably be OK since it's designed to work with copper pipes. It'll probably only be a risk for chrome you may have on certain spa fixtures, unless they are all plastic in your particular spa. Anyway, it sounds like you've got a good handle on the issues so can look out for any problems.

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