Purple flakes in calcium test

swmsks

Silver Supporter
Apr 1, 2021
19
Kansas City, MO
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Just a curiosity question, when I run the calcium test I always see purple flakes, even if I do the 5 drops R-0010 before I start the other drops. Does this just mean I have some metals in the water? Was filled from city water. Does it mean anything for how I should maintain my pool?

Thanks!

AB48D2DD-B401-4F1B-93F6-E68323658B6A.jpeg------------------------------------------
Free Chlorine: 4.0
Combined Chlorine: 0.5
pH: 7.5
Total Alkalinity: 60
Calcium Hardness: 500
CYA: 40
Temperature: 84°F
CSI: -0.07
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
28,582
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Calcium Hardness Test Interference - interference from copper and iron can cause a fading endpoint and some color changes before the final endpoint.

Take your water into a pool store and have them test it for metals.
 

swmsks

Silver Supporter
Apr 1, 2021
19
Kansas City, MO
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
@ajw22 I am more curious if I am getting a good Calcium reading with it turning purple instead of blue? If I let it sit for a few minutes eventually it turns blue.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,479
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The procedure for fading endpoint is to do 5 drops of R-0012 before adding anything. Then you add 10 drops of R-0010, 3 drops of R-0011L and then titrate with R-0012. Add the initial 5 drops to the result.

When the titrant clumps like that in solution it’s an indication of high mineral hardness (calcium and magnesium). One way to reduce the interference is to dilute the sample with DISTILLED water in a 1:1 ratio and then do the test. You then double your final result to get the correct answer.
 

swmsks

Silver Supporter
Apr 1, 2021
19
Kansas City, MO
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Thanks, I missed the distilled water idea in the instructions. That got me a 300, x2 = 600. Time to replace some water? Thanks!
 
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