Yes spirulina is good for high blood pressure and I've noticed my blood pressure going back to regular levels after eating spirulina.
Eating spirulina can also help lower your risk for heart disease, strokes and heart attacks since high blood pressure is a leading cause of strokes, heart attacks and heart disease.
Spirulina can also help boost your bodies immune system to fight off viruses and other bacteria which prevents sickness as well as helping prevent kidney disease.