I added 28# of Boric acid to my pool yesterday. Per pool math, 50 ppm should be 29# and change (477 ounces). Since I've noticed that using pool math with my estimated volume always causes me to overshoot just a touch, I decided to hold back the extra pound and let everything mix up and test this morning.
I have the Lamotte strips (bone dry, broke the seal on them this morning)
I tested a glass of tap water to make sure I could read the color correctly. The color for 0 borates was dead on in tap water and easy to read.
When I got to the pool water, it was a different story. I'm having a hard time distinguishing between the 30 ppm and 50 ppm shade. It looks similar to the 50 ppm shade, but the whole pad is lighter overall. Hard to describe.
I can run another test later and post pics to see if anyone with better eyes than me can tell me whether they can read it.
1. Does anybody using borates and these strips have tips and tricks for getting a good read? (i.e., leave it in the water for a longer/shorter time; read in sunlight/shade/room light, etc)
2. Is there a good resource for a drop test? I have found a couple of threads here. All of them point back to Piscines Apollo, who appears to no longer be selling the drop test. To date, I have found drop tests to be much easier to read and more consistent than strip tests. I would be willing to spend a few extra dollars to get a good drop test.
- - - Updated - - -
Just did the math again and it looks like 477 ounces is 29.81 pounds (or roughly 29 pounds, 13 ounces). This would mean I held back 1 pound, 13 ounces from Pool Math's recommendation. Is it worth tossing another 2# in today and testing again? Or at shades separated by 20 ppm or so, is the precision too broad for me to think holding back roughly 6% of the suggested amount would make a difference?