# KNO3: dry dosing vs. liquid dosing



## trilinearmipmap (Mar 8, 2005)

I need to dose potassium nitrate about 3X per week, it is more convenient to dose it as a pre-made solution rather than measuring it out dry each time, however I was wondering if this will cause any problems. Is the potassium nitrate stable in solution or will it be broken down by bacteria?


----------



## hoppycalif (Apr 7, 2005)

Dose it however you wish. I assume you find pouring a liquid into a measuring cup easier than dipping a spoon into a powder, so you should dose it as a liquid. It isn't an organic compound, so it should be stable in water for a long time.


----------



## BryceM (Nov 6, 2005)

Spend a little time doing the math and make up a big batch of stock solution. Then you'll know that Xml gives you X ppm in your X gallon tank.

Personally, I made up a single solution containing both nitrate and phosphate after tracking concentrations over several weeks with Lamotte kits. I wanted enough to always have a slight surplus, but no so much that a 50% WC didn't take care of it.


----------



## RuslanJamil (Oct 30, 2005)

I normally mix up a 5% solution of NO3 derived from KNO3. That way, 1 mL for each 10L of water will increase NO3 by 5ppm. Previously, I was using a 1% solution so I had to dose 5 times as much.

Only problem is that the 5% solution will have some white fungus like strands after some time. Anyone know what that is? Does not seem to create any problems though.


----------



## Sherri W (May 8, 2006)

Hmm, I noticed white strands in my Flourish nitrogen just this morning? I'll also post the question to Seachem .


----------



## trilinearmipmap (Mar 8, 2005)

So in terms of volume not weight (I don't have a scales just teaspoon measures) how much potassium nitrate per litre of water will make a 5% stock solution? And how much fleet to add to the stock solution so the potassium nitrate and the phosphate are being doses in the proper ratio?


----------



## trilinearmipmap (Mar 8, 2005)

OK chemistry was always my worst subject, can somebody check my math. I want to make a 5% potassium nitrate stock solution:

5% = 5 grams/100 mL = 50 grams/Litre

1 teaspoon potassium nitrate = 5.2 grams

9.6 teaspoons potassium nitrate in 1 Litre of water = 5% solution


----------



## RuslanJamil (Oct 30, 2005)

50 g/L of KNO3 will give you a 5% solution of KNO3. Personally, I find it much more useful to make a 5% solution of NO3. Just multiply by 1.63 since KNO3 is only 61.4% NO3 (1/0.614=1.63).

So, you need 81.45 g in one liter of water or approximately 15.7 teaspoons (assuming the 5.2 g per teaspoon of KNO3 is accurate).


----------



## Left C (Jun 14, 2005)

I use Chuck's calculator: http://www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm


----------



## banderbe (Nov 17, 2005)

trilinearmipmap said:


> I need to dose potassium nitrate about 3X per week, it is more convenient to dose it as a pre-made solution rather than measuring it out dry each time, however I was wondering if this will cause any problems. Is the potassium nitrate stable in solution or will it be broken down by bacteria?


I find it far more convenient to use a pre-mixed solution. I can control the exact amounts of NO3 and PO4 and know that the ratio will always be the same no matter what.. then it's a simple matter to get a 10ml oral syringe from walMart or walgreens, draw up however many mls you want, squirt in the tank and you're done.

Way easier and faster than getting out measuring cups, opening zip loc bags, dipping, leveling off, dumping in the water, not being as accurate, having to close up everything, clean up any powder that my have spilled, etc.

I've done both, powders suck.


----------



## trilinearmipmap (Mar 8, 2005)

Thanks for the help.

I plugged RuslanJamil's numbers into Chuck Gadd's calculator:

15.7 tsp of potassium nitrate in 1 litre of water for the stock solution

According to this, each mL of stock solution in my 75 gallon tank will give 0.19 ppm Nitrate.

So to get 5 ppm nitrate I need to dose about 25 mL.


----------



## RuslanJamil (Oct 30, 2005)

Chuck's calculator assumes that one teaspoon of Potassium Nitrate is equivalent to 5.6 g instead of 5.2 g. Therefore, to get the 5% NO3 solution, you need to add 14.5 teaspoons instead of 15.7 teaspoons. What we actually want is 81.45 g of KNO3 for each liter of stock solution.

75 gallons is equivalent to about 280 liters so you would need about 28 mL to get 5 ppm. In reality you actually need less since some of the volume would be made up of substrate and hardscape.


----------



## trilinearmipmap (Mar 8, 2005)

Thanks.


----------

