[Lugnut]

That might sound dumb but most of the places that sell everything else do not sell just K in a dry form. Am I missing something? I have a gallon bag of muraite of potash,but I have no idea how much of that to use so I would like to buy what I need.

 

[freph]

I'm not sure if you CAN get raw potassium as it's a metal and if you could it'd probably be from a lab supply store or something of that nature. You could probably get away with using K2SO4 which according to GLA is 44.9% potassium.

 

[jmowbray]

I don't think you want to add pure potassium to your tank as it is quite reactive with water.

 

[Kathyy]

Muriate of potassium is KCl. Usually we use potassium nitrate and potassium phosphate so a source providing just potassium isn't needed.

The Fertilator on APC shows 1 teaspoon of KCl produces 62 ppm per 10 gallons.
http://www.aquaticplantcentral.com/forumapc/fertilator.php

 

[Lugnut]

Well that makes more sense then.. I always read add more 'K' and I am thinking where the heck do I get just K. Should I use the Muriate or just be fine with KNo3

 

[JimG]

Potassium nitrate and potassium phosphate should give you more than enough potassium. Use potassium sulfate if you want to dose potassium without also dosing nitrates or phosphates.