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**To**:**<Aquatic-Plants at actwin_com>****Subject**:**Re: K+ weights analysis****From**:**Thomas Barr <tcbiii at earthlink_net>**- Date: Thu, 08 Feb 2001 00:15:10 -0800
- In-Reply-To: <200102072048.PAA20452 at actwin_com>
- User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022

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

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