Borate test

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Sdhb

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Jul 20, 2023
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Canada
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Salt Water Generator
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Hayward Aqua Rite (T-9)
Just wondering about any quirks with the manitol test..

I added enough borax that my borate level should have hit 50, but am consistantly finding the manitol test indicating actual levels closer to 35-40ppm.

Is it just me? I am a bit nervous to add what is required to bring it up to 50, in case somehow my Manitol test result is underestimating the true ppm.
 
It takes a bit of practice to get the colors right. When you go from the acidic yellow state to the baby blue state before adding the mannitol, you need to be very careful with adding the r-0010 because there’s no buffer in the water and the reagent is very concentrated so the color changes in just one or two drops. If you go too far past the baby blue then your count will be off when you start the titration after adding the mannitol.

You also want to make sure that when you add the R-0009 at the beginning that you are getting rid of all the carbonate alkalinity. This requires knowing the TA of the water and adding enough R-0009 to drop the TA to zero. So if your TA is 80ppm, you should probably be adding at least 8-9 drops of R-0009 at the beginning to make sure all of your carbonate alkalinity is neutralize.

Also, as @PoolStored said, a speed stir is a must for this test. Hand swirling won’t cut it.
 
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mgtfp said:
Maybe your R-0010 drop sizes are off. You could try ordering a new bottle.
Click to expand...
Possible. But I'm using that bottle for all other tests and not seeing anything strange, so I think unlikely?

I just did the test again, stopped at step 5 and kept the sample so I'd have a baby blue reference sample. Then did it again fully to compare the blue starting place with the blue ending places. It took me only 7 drops of r-0010 which means 28 ppm borates. However to date I've added 27kg of borax which should have given me 56ppm. Minimal back washing and splashout.. So I'm really confused. Do I add more? Or is there clearly something wrong with my testing process? Levels attached.

One thing... Does the amount of r-0007 in step 2 need to increase if my fc is not 6ppm? In my case it is 7..not sure if that could swing it?
 

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Sdhb said:
Possible. But I'm using that bottle for all other tests and not seeing anything strange, so I think unlikely?
Click to expand...

R-0010 is (apart from the borate test) only used as a buffer in the CH test, not as a titrant, the exact amount is not critical in this test.


Sdhb said:
One thing... Does the amount of r-0007 in step 2 need to increase if my fc is not 6ppm? In my case it is 7..not sure if that could swing it?
Click to expand...

You can try an extra drop, can't hurt. But high FC would just make the indicator not work at all, I don't think that's the issue.
 
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mgtfp said:
R-0010 is (apart from the borate test) only used as a buffer in the CH test, not as a titrant, the exact amount is not critical in this test.




You can try an extra drop, can't hurt. But high FC would just make the indicator not work at all, I don't think that's the issue.
Click to expand...
So in other words, if my r-0010 drop size is wrong, it wouldn't be readily apparent in other tests... Only the borate test?
 

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Do the ingredients only list sodium tetraborate … nothing else, right? Just trying to rule out anything obvious.

As I’m sure you can see, your numbers are exactly 1/2 what you expect them to be. That suggests some kind of testing error or chems that are not right.
 
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JoyfulNoise said:
Do the ingredients only list sodium tetraborate … nothing else, right? Just trying to rule out anything obvious.

As I’m sure you can see, your numbers are exactly 1/2 what you expect them to be. That suggests some kind of testing error or chems that are not right.
Click to expand...
I did notice that and sort of brushed it off as coincidence. But you're probably on to something. Previously borate levels always tested lower than 50, but never as low as half of what I was expecting.

I used all the borax so don't have the packages, but it's the same one I see being referenced so I think it should be 100%


Is it possible the amount of mannitol could be impacting? I am using a 1/4 teaspoon measuring spoon.. But foreseeable the compactness of the mannitol could be variable. Not sure if that could impact?
 
You can always add an extra scoop of mannitol, it’s ok to add it in excess of what is needed.

Just seems odd to me that it’s exactly half of what you’re expecting.

Try measuring the TA again and then add an amount of R-0009 plus an additional 2 drops to make sure the TA bottoms out completely. With a 50mL sample it will require twice what you measure in the standard TA test (25mL). So if your TA is 70ppm, add (7+2)x2 or 18 drops of R-0009 to your borate test. I suspect it won’t change the outcome but I just want to be 100% sure.
 
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In addition to the manitol, and the TA bottoming out, I also found, that if you use .5mL of the BTB, the whole test works better and I can discriminate color changes better. Both the 009 drops and the 010 drops become VERY clear when you have added enough to get the color change.
 
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I have the btb jar with a little dropper.. Can you estimate how many drops to get to. 5ml?
 

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