Testing Borates with Lamotte test strips

[mr_gunite]

So I added 16 boxes of 20 Mule Team Borax to my water about 3 weeks ago, and tested about a week later using Lamotte strips. The original reading was dead-on 50 ppm.

Last week, I went through my weekly battery of water tests, and the test strip read very slightly darker than 80ppm. (I was guessing maybe 65ppm)
Yesterday, I tested again, and it read slightly lighter than 80 ppm. (I was aghast at maybe 90ppm)

I have not added anymore Borax or Boric acid to the pool at all since my initial dosing. I've only had to lower pH so far, and never had to raise it yet.

Can anyone guess what might be going on here?

Yesterday's test results:
FC - 5
CC - 0
TC - 5
TA - 100
pH - 7.5
CH - 250
CYA - 40
Salt - 2200
Bor - 90??

 

[JasonLion]

The strips can be affected by humidity if the tube of strips doesn't seal well when stored.

 

[mr_gunite]

The tube seems to seal pretty well, and I keep them stored in my basement, so humidity does climb somewhat if the dehumidifier down there isn't emptied quick enough.

I was wondering, does chlorine affect these strips at all? I'm thinking of taking a sample of pool water and dropping a couple chlorine neutralizer drops in first, and then taking a reading. Not sure how valid that will be, but I think it might be worth a try.

Then there's always the horrid possibility that these strips are working correctly and there's way too many borates in my water. Since, in ignorance, I never tested the water before adding 16 boxes of borax, the only solution I can come to is that the 21k gallons of delivered water had borates in it already. I've added 5k-6k gallons of well water to that afterward from both splashout and about a 3k shortage from the original delivery. I never even thought that could be a possibility until now. Since I didn't know the source of two of the truckloads of water, I'm wondering if they pulled the water out of someone else's pool that had added borates to it??

 

[Xexys]

Do the test strips have any information on how to test? For instance, my test strip instructions say to dip the strip in the water and remove immediately. Hold level for 15 seconds and not to shake excess water off the strip. Then, compare strip to the color code on the bottle. My test strips are made by Hach.

 

[mr_gunite]

I'm using the Lamotte strips. I thought they said to dip for 5 seconds 6" deep and then hold level for 15 seconds. The time when I got a reading of 50ppm, I dipped and removed immediately, and then held level for 15 seconds.