Black Powder, 100% water soluble, PH=8-10. Soluble alginic acid ... 18-20% ASD-001 Seaweed Extract Fertilizer Powder with High PotassiumProduct characte Black Powder, 100% water soluble, PH=8-10.Main ... K2O≥18-20%, I≥600ppm, much secondary element and microelements, cytokinin, indole acid, betaine, amino acid and protein. (N,P, ... ) or to buyer’s option. Seaweed Extract Fertilizer Powder with High Potassium