From The Aquarium Wiki
K2SO4 – Potassium sulphate (Potassium sulfate (USA spelling)) : Provides Potassium (K) for feeding aquatic plants.
Quite often in a planted aquarium the plants absorb so much potassium that it becomes a shortage and limits the growth of the plants. So aquarists often add it manually.
To make a typical stock solution add 55g of dry K2SO4 powder to 500ml of RO or distilled water and then add 40ml of this per 100L of tank. This will give you a value of 20ppm (20 mg/l). You would dose 3 times a week when using the EI method.
- Adding potassium sulphate at the rate of 0.011g per litre to a tank will increase the potassium (K) level by 5ppm.
- Example commercial product is 'Sulphate of Potash', a common gardening fertiliser. Typically says it contains K2O (Potassium oxide). But it's really Potassium sulphate. See this example product web site.
- See PMDD for more details.
- See dosage web site: Chuck's - Calculating dosages of fertilizer elements for a planted tank and choose the 'Potassium Sulfate' option
- See Potassium section of : Warning signs of Nutrient Deficiency
- This product is toxic: See PDF Safety Sheet
- Garden shops - Look for 'Sulphate of Potash' and check that the ingredients only say it contains K2O.