Borate testing

[JCarsten]

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.

Failing that:

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?

 

[jblizzle]

If you always overshoot, sounds like you should be lowering the volume of the pool you enter.

From what i read, the borates tests is hard to distinguish as you are seeing.

 

[JCarsten]

Thanks Jason. I am thinking about re-measuring my pool. I have the "clipped" Grecian corners and I entered my measurements based on what the pool builder told me was the shallowest and deepest depths. I have a short, shallow end, then about 1/3 of the center part of the pool is a slope toward the deep end. I was just averaging what he told me was the depth of the shallow and deep ends. I think I may get in with a tape measure and get a depth at shallow, deep and at least one measurement in the center of the slope, then use those numbers for my average depth.

When I overshoot, it's not by a great deal. When I have added MA, I may get a larger ppm drop in TA vs. what pool math tells me. But the overshot is not huge.

For the precision of borate testing, is it that vital? I appear to be in the 50 ppm range. But if I add a little more acid and overshoot a bit, is that a problem? From what I've read here, it's more of a problem to be short of 50 ppm, especially where algae prevention is concerned.

 

[jblizzle]

Exact borate levels do not matter.

 

[chem geek]

For reading the test, it's the hue that is important more than the saturation. The test goes from a Magenta color at 0 towards a pale orange at 80, but 50 ppm still has a tinge of magenta in it while 30 ppm has a more clear magenta tinge. You are most likely where you expected to be based on the amount of chemical you added.

 

[SwimAustin]

While it doesn't matter much right now, it would be good to learn to read the test with a known borate level, because in a year or so, you're going to want to know how much to add to get back to this level. Maybe you could mix up a 30 ppm reference solution to compare too?

 

[bobodaclown]

That was one reason I got a drop based test. Not sure who's offering them now that Apallo isn't shipping to the US.