Calcium hardness

[tcat]

What sort of shelf life do the CH chemicals have (10,11,12)? My 11 seems real thick and I have to squeeze really hard to get drops out. I added 60 drops of 12 before it barely turned light blue. I get a lot of evaporation (since my CYA goes to zero each year), I assumed that would drive CH down. Bad chemicals, or high CH?

 

[Texas Splash]

Unfortunately CH doesn't go down with evaporation. You have to exchange water. As for the R-0011, mine has done that as well. I try to just wipe the tip to try and free it up a bit. I try to replace those CH reagents every year to be safe.

 

[DeanP66]

The CH test is my least favorite of all the test. I'm never sure how far to go once the sample starts to turn blue. I can never tell what the endpoint is.

I prefer to use the Hach total hardness test kit that people use to test their water softeners, but that number includes magnesium as well as calcium hardness. Even still, running the test is much easier for me. I can tell instantly when it's done and then I just deduct a little to guesstimate my CH. The Hach test is measured in grains which equates to 17.1 ppm for 1 grain of hardness. I always look at my previous tests to get an idea how much it has climbed. I still do the Taylor CH test just to see what I get, but the Hach is what gives me more confidence in the results.

 

[salinda]

I run the alternative test for high CH. The asterisked part below.
Calcium Hardness Test
1. Rinse and fill large comparator tube to 25 mL mark with water to be tested.*
2. Add 20 drops R-0010. Swirl to mix.
3. Add 5 drops R-0011L. Swirl to mix. If calcium hardness is present, sample will turn red.
4. Add R-0012 dropwise. After each drop, count and swirl to mix until color changes from red to blue.
5. Multiply drops in Step 4 by 10. Record as parts per million (ppm) calcium hardness as calcium carbonate.
*When high CH is anticipated, this procedure may be used: Use 10 mL sample, 10 drops R-0010, 3 drops R-0011L, and multiply drops in Step 4 by 25.

 

[DeanP66]

I do too, but it's still hard for me to tell when I'm done.

 

[Texas Splash]

I use a speedstir to mix the CH. While that's good for hands-free mixing and great for the reagent, I felt like I would miss the transition. Sometimes, when I know I'm getting close between purple and baby blue, I'll stop the stirrer momentarily which helps me see the color just a bit better. Then I start it again and add a drop or two and repeat. Remember that the CH is kind of like hand grenades .... it just needs to be close. So wondering if it's a CH of 375 or 400 isn't going to break the CSI or anything. Now I'm always sure to wait patiently and watch for that true baby blue color, and if I put an extra drop with no change, I just don't count that last drop or two. I know it's as baby blue as it's going to get and I'm close.

 

[mknauss]

Like Pat, I find if I turn off the Stir device for a few seconds, and restart it, I can get the blue to come out. Not sure why but if I know my CH is around 500 ppm, at the 16th drop or so I will start to turn off the stir device and turn it back on after every drop.

 

[BenB]

I like using the light on the SpeedStir got the CH test. I find the additional light directly up and through the sample is helpful. Obviously it has to be dark outside (or bring it inside to a dark room) for the light to be visible.

 

[djdonte]

I use the speed stir indoors, using the light for that test. First it turns purplish but the test isn’t done until it’s full blue. I replace the chemicals every few years. The dark reagent does get hard to squeeze after a while. Try wiping the tip real good or removing the tip and cleaning it. Replacement wouldn’t hurt either. Honestly, I keep my kit inside in AC and I didn’t see any different in results between new chemicals and 3 year old ones but YMMV.