Potassium sulfate (K2SO4), also called sulfate of potash, arcanite, or archaically known as potash of sulfur, is a non-flammable white crystalline salt which is soluble in water. The chemical compound is commonly used in fertilizers, providing both potassium and sulfur.
In Spirulina cultivation, K2SO4 is used in the famous Zarrouk formula which was used by NASA in the 1960s.
Where to Get Potassium Sulfate
K2SO4 can be difficult to find in shops, and will usually be mixed with a bunch of other minerals which aren’t necessarily needed for spirulina cultivation. So, to make things easier, here are a few suppliers that sell (almost) pure potassium sulfate in crystalline form on Amazon.
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