Borate Drop Test False Reading?

[aspiringnobody]

Maybe @chem geek or @JoyfulNoise can chime in, but I'm wondering if something in the water can produce a false positive on the BTB/Xylitol drop test. I've either got ~30ppm in my fill water or something in my water is causing the test to read high.

Source water is:
ph 7.2-7.4
CH 500-600
TA 250
FE... Lots
MN... 1-2ppm
CU 0
H2S present in unknown quantity.

The reason I'm asking is, the number appears do drop after going through greensand reduction and an ion exchange resin, neither of which should lower the borate significantly to my knowledge.

What else could be going on?

 

[JoyfulNoise]

Maybe @chem geek or @JoyfulNoise can chime in, but I'm wondering if something in the water can produce a false positive on the BTB/Xylitol drop test. I've either got ~30ppm in my fill water or something in my water is causing the test to read high.

Source water is:
ph 7.2-7.4
CH 500-600
TA 250
FE... Lots
MN... 1-2ppm
CU 0
H2S present in unknown quantity.

The reason I'm asking is, the number appears do drop after going through greensand reduction and an ion exchange resin, neither of which should lower the borate significantly to my knowledge.

What else could be going on?

I can tell you that my tap water (municipal water, no boron) shows zero borate on that test so my guess is the high iron and manganese levels are interfering with the tests. Greensand can reduce iron and manganese levels but if they are very high, it won’t eliminate them. Metal interference can mess up a lot of chemical tests. Even the CH test is susceptible to interference from iron if too much of it is around.

I suggest you use an alternative method and try the strips. Otherwise you just have to guesstimate based on logging additions and water loss. Boron only leaves the water when you exchange it out.

 

[aspiringnobody]

I've got the strips on order now. Arrive Thursday. I'll let you guys know. It's certainly possible that there is boric acid or some other form in our ground water; but I don't know of any way to verify that with any certainty.

I assume the pool store's colorimeter is susceptible to the same interference?

 

[JoyfulNoise]

I've got the strips on order now. Arrive Thursday. I'll let you guys know. It's certainly possible that there is boric acid or some other form in our ground water; but I don't know of any way to verify that with any certainty.

I assume the pool store's colorimeter is susceptible to the same interference?

Yep. I would definitely NOT trust the pool store.

Have you had your raw well water tested by an outside company? There are testing companies that can do a whole slew of chemical and biological tests on well water samples. If your well water is contaminated as much as you indicate, I wouldn’t feel safe drinking it without knowing exactly what’s in it. Whenever iron and manganese are present, arsenic is not uncommon. Boron would be highly unusual in well water as the natural minerals that contain soluble boron are usually found only in evaporite deposits in arid regions with seasonally dry lake beds (Boron, California....home of 20 Mule Team Borax). Boron in a well would suggest an industrial pollutant.

Growing up, my parents had a well. The water always had iron in it but, a decade or so later, there was a local fuel oil company about 5 miles away that got caught with leaking storage tanks (large industrial oil tanks). The ground water around that facility was heavily contaminated with organic and metallic pollutants. They were forced to remediate the pollution and had to setup a fund for every home within the area to have annual water tests. Sure enough, another few years later, my parent’s well started to show contaminants. Luckily a new development was built that brought with it the “last mile” of municipal water line and so my parents were able to hook up to it and abandon the well. It still cost a bundle of money to run a line from the street to the house, but at least the water was clean.

 

[aspiringnobody]

Our ground water comes from glacial tillings so depending on what the glacier decided to drop on our property the rock around or well could be literally anything in from our latitude all the way up to the Hudson bay. Certainly possible that some ancient dry seabed ended up under our house.

The water has been tested, yes. I'm not sure if borates are on the list since the US doesn't have a federal standard for maximum allowable borates in drinking water. We don't drink it anyway.

I'll look into having another sample done, it's been a few years.

 

[JoyfulNoise]

You’d want to look for boron testing. Some water testing companies have tiered pricing so that basic tests are lower cost but more advanced testing will cost more.

You are correct that EPA does not regulate boron as either a primary or secondary contaminant. It’s not currently on the CCL-4 list but the newer CCL-5 list is still under open comment period so it could, in theory, make it on there.

From agricultural standpoint, soil boron levels in excess of 2-5ppm will start to cause plant distress to occur. However, most soils in the US are boron deficient so it's not usually a problem. Aquatic environments could be hurt by excess boron but I suspect the levels needed would be unusually high and would require a significant source of contamination to be present such as one might find in an industrial setting.

Keep this thread posted if you get any testing results. I did go back and test both my raw municipal water and water after my softener (removes mineral hardness and chlorine/chloramine) and both show zero boron. My pool is at 60ppm and when I test that, it’s spot-on. So my water softener has no effect on the test. I even added a few granules of borax to the test water with mannitol in it and you could see the indicator going from blue to yellow indicating the pH drop you’d get from boron complexing with the mannitol and creating free protons (acidifying the sample).

 

[aspiringnobody]

You’d want to look for boron testing. Some water testing companies have tiered pricing so that basic tests are lower cost but more advanced testing will cost more.

You are correct that EPA does not regulate boron as either a primary or secondary contaminant. It’s not currently on the CCL-4 list but the newer CCL-5 list is still under open comment period so it could, in theory, make it on there.

From agricultural standpoint, soil boron levels in excess of 2-5ppm will start to cause plant distress to occur. However, most soils in the US are boron deficient so it's not usually a problem. Aquatic environments could be hurt by excess boron but I suspect the levels needed would be unusually high and would require a significant source of contamination to be present such as one might find in an industrial setting.

Keep this thread posted if you get any testing results. I did go back and test both my raw municipal water and water after my softener (removes mineral hardness and chlorine/chloramine) and both show zero boron. My pool is at 60ppm and when I test that, it’s spot-on. So my water softener has no effect on the test. I even added a few granules of borax to the test water with mannitol in it and you could see the indicator going from blue to yellow indicating the pH drop you’d get from boron complexing with the mannitol and creating free protons (acidifying the sample).

I suppose the question would be what could cause the blue to yellow transition when xylitol is added that's not boron.

The county is checking with their lab to see if they can do a boron test.

Pb, bacteria, and pH cost $115 which is insane so I'll have to find another option.

 

[JoyfulNoise]

The blue to yellow transition happens when boron reacts with the diols (-OH groups) on the linear sugar backbone. The boron bonds with the oxygen atoms and kicks off the protons (H+). I’d have to research the chemistry some more but it is possible either the dissolved manganese or iron with the right oxidation state could cause a similar reaction thus acting as a positive interference (creates more acid and takes more drops of R-0010 to get back to neutral pH).

Testing for boron will likely cost more. It’s going to require something like high performance liquid chromatography or plasma emission spectroscopy to determine the various levels. Titration testing only really works when you can have distinct chemical reactions. Dissolved metal ions will screw up a lot of quantitative wet chemistry tests.

 

[aspiringnobody]

The blue to yellow transition happens when boron reacts with the diols (-OH groups) on the linear sugar backbone. The boron bonds with the oxygen atoms and kicks off the protons (H+). I’d have to research the chemistry some more but it is possible either the dissolved manganese or iron with the right oxidation state could cause a similar reaction thus acting as a positive interference (creates more acid and takes more drops of R-0010 to get back to neutral pH).

Testing for boron will likely cost more. It’s going to require something like high performance liquid chromatography or plasma emission spectroscopy to determine the various levels. Titration testing only really works when you can have distinct chemical reactions. Dissolved metal ions will screw up a lot of quantitative wet chemistry tests.

Anything I could add to the solution to change the metal ions to one of the less reactive states? I have some EDTA although I'm not sure if that would be very helpful. If it's the metal ions I would expect the number in my pool to decrease with time as the chlorine reduces them out of solution and they get filtered out, however the levels seem to be increasing over time so that doesn't make sense.

A conundrum for sure.

 

[JoyfulNoise]

Anything I could add to the solution to change the metal ions to one of the less reactive states? I have some EDTA although I'm not sure if that would be very helpful. If it's the metal ions I would expect the number in my pool to decrease with time as the chlorine reduces them out of solution and they get filtered out, however the levels seem to be increasing over time so that doesn't make sense.

A conundrum for sure.

The R-0012 CH titrant is essentially EDTA. You could try adding a few drops to the test sample after adding the R-0007 de-chlorinating drops in the first step to see if it binds up any metal ions and makes a difference to the test. Not really sure if that will work or not but you could always try.