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Re: K+ weights analysis

Regarding adding K+ by estimation rather than water testing.

First the assumptions:

1) There's a big error in the 1/4 teaspoon part(are all 1/4 teaspoons going
to be created equal?).

2) Assumption No# 2 is 100% purity. The brands used are relatively pure.

3) It is only the water volume here, not the the tank size! Gravel will not
have any K going into it! These assumptions are for any substance being
measured by a teaspoon method.

4) most folks are not going to be all accurate and perfect each time they
toss the 1/4 teaspoon in there.

Remember that tap has a small amount and many trace fertilizers also have it
added. this will add to your test reading if using a kit.


But taking it a step further and seeing if I added just a little bit more or
less to see how this might affect things, I think it gets close enough,
perhaps 2ppm or so for the 20 gallons of water addition. This is still
better than the test kits for K+.

Anyhow the results:
--------------------------------------------------------------------
Products tested:

Cooke's brand stump remover (KNO3)
Green All's Sulfur of Potash (K2SO4)
Both products were heated above 100 C for 15 minute then cooled. This should
remove most traces of water.

Average for 10 samples of K2SO4 level 1/4 teaspoons= 1.8766 grams

2 x K+ =78.1966g/mole
Total for the K2SO4= 174.2602g/mole
% K = 78.1966/174.2602= .4487 x 100% = 44.87% K per unit volume.
So 1 gram in a liter would equal 448.7 ppm K. There's 3.7843 liters in one
gallon.

Formula used:
***
448.7/(water volume in liters) x 1.8766grams (per 1/4 teaspoonful)=
concentration in ppm.
***

So if you have a tank with 20 gallons of water and add a 1/4
teaspoon(@1.8766g per spoon full) of K2SO4 you will now have added an extra
11.12ppm of K+ to the tank.
448.7ppm/75.686liters in 20 gallons x 1.8766 grams in 1/4 teaspoon =
11.12ppm

20 gallons= 11.12ppm K+
40 gallons= 5.56 ppm K+
100 gallons= 2.23 ppm K+
-----------------------------------------------------------
KNO3:
K+ = 39.0983 g/mole
NO3- = 62.00494 g/mole
% K = 38.67% 
% NO3 = 61.33%

Mass average of 10 samples of 1/4 teaspoon(level) of KNO3 = 1.480grams
or about 386.7ppm of K+ and 613.3ppm of NO3 in one liter.

Formulas used:
***********
For K+: 386.7/(volume of water in liters) x 1.4800 grams (per 1/4teaspoon)=
concentration in ppm.
For NO3-: 613.3/(volume of water in liters) x 1.4800 grams (per 1/4
teaspoon)= concentration in ppm.
*************
 
20 gallons= 7.56 ppm of K+, 11.99ppm of NO3-
40 gallons= 3.78 ppm of K+, 6.00ppm of NO3-
100 gallons= 1.51ppm of K+, 2.40ppm of NO3-

Hope this may clear some of it up:) I still say there's no need for a test
kit.
regards, 
Tom Barr