Slam single drop testing

[ka8yiu]

Long ago, I read a way to test during a SLAM to conserve your reagents. What is that process? I recall one drop for one ppm.

 

[jimbethesda]

Use 5ml sample instead of 10ml.

 

[gonfishin]

What is that process? I recall one drop for one ppm.

5ml of pool water
1 scoop of poweder (just like the 10ml test)
1 drop of 0871 = 1 ppm FC

 

[mariane]

Curious question for the mods - Is there a reason to not do this all the time? 1 drop = 1 ppm

 

[IceShadow]

I can see the downside is that it's going to be less precise and since the margin of error on the test is a drop or so, more inaccurate. If your FC needs to test up in the 20s it makes sense to do it to conserve reagents but typically you don't want to know your pool is somewhere 5-7ppm, and would rather know it's somewhere 5.5-6.5ppm.

 

[Richard320]

Curious question for the mods - Is there a reason to not do this all the time? 1 drop = 1 ppm

That's like using a tape measure that doesn't have fractions on it.

Maybe you're at 3.3 FC.

Using a 10 ml sample, at 6 drops, there's still the slightest tinge of pink left. The next drop means 3.5. because there's no doubt then that it's clear.

Using 25 ml sample, it says you're at 3.4

Using 5 ml it will say 4.

That's a pretty substantial difference when you're at normal daily levels. Being off by that much during the SLAM is no big deal.

 

[Donldson]

As you get smaller sample sizes the requirement for precise sample sizing increases. Once you get down to 5 ml you have to be virtually exact to even get a +/- 1 ppm accuracy. If you are off by even a quarter mil it can throw off the entire test by potentially several ppm, depending on the FC level being measured. This can be acceptable when in SLAM mode, but for normal operation it is far too much accuracy lost to save a few drops of reagent.

 

[mariane]

Thanks All.
I can see when during a SLAM and the numbers are high and one is low on regent it could "stretch" it until the refill comes in the mail.