I have a Taylor K2006, and after my most recent water change noticed that when performing the calcium hardness test, there seems to be some coagulation (suspended droplets of different color) occurring with the sample tube when adding the titration agent. Is this a known interference? Expired/bad reagent?
Taylor Calcium Hardness test coagulation?
- Thread starter FritzM
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- Sep 23, 2015
- 1,649
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- 20000
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- Astral Viron V25
Does the coagulation appear when the R-0010 or R-0011 dye is added or only after when you add the R-0012 titrant reagent?
Sounds like interference from copper in the water, which your signature says you are using. Try adding two drops of R-0012 before you add the R-0011L indicator dye and see if that helps. Remember to include the 2 drops of R-0012 in your total when you figure your results.
While silver has some good algaecidal and sanitary properties in a hot tub, copper is universally discouraged here. Interfering with the CH test is the least of the problems it causes.
While silver has some good algaecidal and sanitary properties in a hot tub, copper is universally discouraged here. Interfering with the CH test is the least of the problems it causes.
Thanks, Donaldson. FWIW, this was first noticed after a fresh fill, and with the ionizer disabled. I have not run the CH test in a lttle while though - since it pretty much stays put I only test CH after fills or partial water replacements.
Previously, I had noticed the copper concentration would keep creeping up, even with the ionizer on its lowest setting, so at some point I just unplugged it. It had not yet been reactivated on this fill. I had previously seen interference more like a fading endpoint, which I had assumed was Cu interference, but without this coagulation visible.
I will try a test on straight fill water today I think and see if it does the same thing?
Re. copper: I think I inderstand the objections here (masking poor sanitation, staining potential at higher concentrations if pH not carefully controlled, test interferences). If my wood tub were lined and I could tolerate the higher standing FC concentrations advocated for TFP spas I would just dispense with it. I have been trying to learn as much as I can from TFP methods, which seem worked out and very effective, and work out a effective method tailored for my unlined tub (let Cu/Ag at reasonable concentration keep algae down, sanitize after each use with dichlor/bleach for the other bugs, oxidize weekly to clear waste, and run a much lower standing FC concentration stabilized with some CYA). It sure would be easier with straight TFP, but I think it would pulp my tub if I played strictly “by the book”!
Previously, I had noticed the copper concentration would keep creeping up, even with the ionizer on its lowest setting, so at some point I just unplugged it. It had not yet been reactivated on this fill. I had previously seen interference more like a fading endpoint, which I had assumed was Cu interference, but without this coagulation visible.
I will try a test on straight fill water today I think and see if it does the same thing?
Re. copper: I think I inderstand the objections here (masking poor sanitation, staining potential at higher concentrations if pH not carefully controlled, test interferences). If my wood tub were lined and I could tolerate the higher standing FC concentrations advocated for TFP spas I would just dispense with it. I have been trying to learn as much as I can from TFP methods, which seem worked out and very effective, and work out a effective method tailored for my unlined tub (let Cu/Ag at reasonable concentration keep algae down, sanitize after each use with dichlor/bleach for the other bugs, oxidize weekly to clear waste, and run a much lower standing FC concentration stabilized with some CYA). It sure would be easier with straight TFP, but I think it would pulp my tub if I played strictly “by the book”!
It seems to appear only when I add the R-0012 titrant, although I'll look closer today -- perhaps it is occurring earlier, and only becomes visible once there is color contrast during the titration?
Test on fill water (Oakland CA tap water) did not coagulate; CH somewhere in the 20-30 range. Problem seems a little less severe today, about 48hrs after fill, though I did refresh the batteries in my speedstir as well ha! You can't really see the coagulation when the water is spinning at high speed; it only becomes apparent when the circulation slows down. So maybe its been going on for a while and I only recently noticed it. At least it seems my reagents are fine.
So, copper interference seems likely. I'm puzzled how enough copper to interfere with the test would have survived a complete drain and refill, though! Hmm...
So, copper interference seems likely. I'm puzzled how enough copper to interfere with the test would have survived a complete drain and refill, though! Hmm...
- Sep 23, 2015
- 1,649
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
I would think it is possible for copper to bind to the timber and be released into the new fill water.
Metal ion interference causes a “fading end point” where the sample may turn purple or blue then turn back to red/pink.
See the extended CH test notes; https://www.troublefreepool.com/content/218-Calcium-Hardness
The R-0010 raises the pH and precipitates magnesium. I was initially thinking it had something to do with high magnesium or co-precipitation of calcium and am sure I’ve read something similar. Given there was no coagulation with the town water one would assume it must be a metal ion interaction and I’m thinking it is an interaction of all of the above.
Do you have a definite end point? What is your CH at?
Hears a bit more from Chem Geek; https://www.troublefreepool.com/thr...recipitation calcium test&p=730596#post730596
Metal ion interference causes a “fading end point” where the sample may turn purple or blue then turn back to red/pink.
See the extended CH test notes; https://www.troublefreepool.com/content/218-Calcium-Hardness
The R-0010 raises the pH and precipitates magnesium. I was initially thinking it had something to do with high magnesium or co-precipitation of calcium and am sure I’ve read something similar. Given there was no coagulation with the town water one would assume it must be a metal ion interaction and I’m thinking it is an interaction of all of the above.
Do you have a definite end point? What is your CH at?
Hears a bit more from Chem Geek; https://www.troublefreepool.com/thr...recipitation calcium test&p=730596#post730596
Thanks, Steve. The endpoint I get doesn’t fade, but it is pretty hard to see (purplish-red to purplish-blue, not the proper baby blue endpoint that I do see with town water).
To the best I can still read the test it puts my CH around 150/160, which is not too far from what I expect, having started with town water around 20-30 and added enough calcium chloride in one shot to raise it about 100 ppm based on volume estimate of the tub.
For now I’ll leave the ionizer disconnected, and I’ve put a cuprizone copper test kit on order from Taylor to see if I can get on top of it quantitatively.
I’ll also go see if I can digest Chem Geek’s post. Thanks for the link!
To the best I can still read the test it puts my CH around 150/160, which is not too far from what I expect, having started with town water around 20-30 and added enough calcium chloride in one shot to raise it about 100 ppm based on volume estimate of the tub.
For now I’ll leave the ionizer disconnected, and I’ve put a cuprizone copper test kit on order from Taylor to see if I can get on top of it quantitatively.
I’ll also go see if I can digest Chem Geek’s post. Thanks for the link!
Hi Donldson — no, did not seem too. Seems like it should though, from what I’m learning? Next time I run the test I’ll try to putting in even more of the titrant up front and see if that helps.
Okay, I ran the CH test again this afternoon, and put ten drops of titrant in up front. The endpoint color was much better and easier to read (CH 160). Coagulation still occurs; here’s a pic of this test:
- Sep 23, 2015
- 1,649
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
Always love a good pic and think thats quite normal but I’ll have to run my CH test this weekend to be sure. I’d thought I’ve seen what you had described when running the CH test without the R0010 but that was a long time ago. I’ll have a play and see what I get this weekend.
It’s good you’ve consistently got 160ppm for CH and that it matches your statistical value. Yah.
There’s still a good chance you’ve got a healthy case of divalent metal interference or interaction. I’m not a Taylor tech but I found an old thread from one of TFP’s finest that suggested there is a chelating agent for divalent (Valency of 2 or +2) transition metals other than calcium in the R0012. I’m thinking your seeing a chelated copper dye complex in suspension.
When you get your copper test be sure to run your pump for a bit and manually brush the bottom before taking a sample.
It’s good you’ve consistently got 160ppm for CH and that it matches your statistical value. Yah.
There’s still a good chance you’ve got a healthy case of divalent metal interference or interaction. I’m not a Taylor tech but I found an old thread from one of TFP’s finest that suggested there is a chelating agent for divalent (Valency of 2 or +2) transition metals other than calcium in the R0012. I’m thinking your seeing a chelated copper dye complex in suspension.
When you get your copper test be sure to run your pump for a bit and manually brush the bottom before taking a sample.
- Sep 23, 2015
- 1,649
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
If you remain worried about the reagent useful shelf life - firstly don’t, you’ve got a consistent and repeatable result. Secondly, and more for trivia the R0010 is NaOH and good for almost ever as long as it’s sealled, the R0011 is good for 24 months but if it’s a deep blue your good to go and the R0012 is mostly RDTA and you’ll get at least 24 months from it.
First, this forum has been a god send. I inherited my first pool last spring, and after finding this forum it has been a breeze and relatively cheap to maintain. I try to point every pool owner I meet to TFP.
I came today to ask the same exact question. My CH test also looks identical to the above picture when I stop the speed stir, and the little pink coagulations cannot be seen while it is spinning. No fading endpoint, and have run it several times with the same result (225CH after adding 15lbs of Hardness Plus). Of course I had two separate leslies stores test the water and they both gave drastically different results on every test except FC and PH. I was not sure I trusted my test because it dropped from 275 in August to 120 before adding the Hardness Plus yesterday, but it appears my test was accurate.
I came today to ask the same exact question. My CH test also looks identical to the above picture when I stop the speed stir, and the little pink coagulations cannot be seen while it is spinning. No fading endpoint, and have run it several times with the same result (225CH after adding 15lbs of Hardness Plus). Of course I had two separate leslies stores test the water and they both gave drastically different results on every test except FC and PH. I was not sure I trusted my test because it dropped from 275 in August to 120 before adding the Hardness Plus yesterday, but it appears my test was accurate.
- Sep 23, 2015
- 1,649
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
Sorry my bad, yes I meant EDTA.
I ran the CH test twice on the weekend and got the same. 10ml samples with less dye and two different CH levels, both with the same result. I kept thinking that I’d seen that before, every time I do the test.
I’ll call it normal, an EDTA/calcium/dye complex?
I ran the CH test twice on the weekend and got the same. 10ml samples with less dye and two different CH levels, both with the same result. I kept thinking that I’d seen that before, every time I do the test.
I’ll call it normal, an EDTA/calcium/dye complex?