LaMotte Test Kits

[Plantbrain]

Now before ya ll go runnign off thinking that the LAMOTTE KITS ARE INFALLIABLE, they are not, no test method is.

AP, Hagen or otherwise.

You should still make a series of standard solutions.
Make at least a 5ppm and a 20ppm etc.

See how that compares.
The standard is easy as adding the weight of KNO3 to a large container(makes your weight measurements less problematic), say 1 liter. Use the dosing calculators to see how much is needed.

Should be about 0.233 grams KNO3 for a 10ppm solution in 1 liter of DI water.

I do not use cals just close estimates so that should be fairly close tyo see if the test kit is funny.

To make diltutions: take 5mls sample from the 10ppm and add it a 5ml DI water sample. Now you have 10mls of 5ppm NO3.

Dilute this further with DI water again, say 5mls of the 5ppm water and add 5 mls of DI water, now you have 2.5 ppm and so on..........

Always start at the highest concentration, then make your dilutions.........this prevents errors since the weaker dilutions will have less errors as you progressively dilution the standards.

The high and low standard ppm solutions should match if the test kit is decent.

This must be done for any water measurement science etc, andf calibration of the pH meters etc is the same essentially, they use the 4.0ph and the 7.0 pH solutions to calibrate the probes.

Regards,
Tom Barr

 

[dskidmore]

Of course, you need a resonably accurate scale to create the control solution....

 

[czcz]

We have densities for most compounds in the hobby. Measuring a control solution by levelled teaspoon is more than accurate enough for this purpose. Dare I say more accurate than the %error of any test available to the consumer, even when factoring in impurities (of the compound) and quality control (of the teaspoon).

Tom Barr's suggestion of dilution also lowers user error, of course. Easier to percisely measure 5mL than 1mL from solution for the testing target, for example.

 

[Plantbrain]

Of course, you need a resonably accurate scale to create the control solution....

Gram scales that are accurate to .01 grams are fine........and cheap.
You can scale up your sample size and assume that a levels teaspoon of KNO3 = 1.67 grams also.

So you can adjust the amount of DI water that is added to to get 20 pmm.
Roughly 38 liters.

That might be easier than finding/buying a scale etc.


Regards,
Tom Barr