Regarding dosage nomercy.
Spirulina: A maintenance dosage of Spirulina is 3 -- 5 grams per day. Although their nutritional profile may appear to be quite similar, Spirulina and Chlorella are completely different foods. Spirulina is great before a physical workout. I take 5 – 6 grams religiously before any kind of physical training. Stamina, endurance and recovery are significantly improved with Spirulina. After a strenuous workout where the body is pushed to its limits, an additional 10 – 20 grams should be taken during the following 24 hours to rebuild the body and muscle tissue that has been torn down.
Spirulina should also be taken 15 – 30 minutes before a meal to help prepare the stomach for proper digestion since it also helps accelerate the reproductive rate of probiotics.
Maintenance Dosage: 3 – 5 grams/day
Significant Part of the Diet: 6 – 10 grams/day
Immune System Builder: 11 – 14 grams/day
Primary Source of Protein : 12 – 19 grams/day
Healing Purposes: 20 – 25+ grams/day
Also great before a workout
But then again a company wants to sell you as much as they can to make a profit but there are many sites giving dosages between 500mg- 25 gms which would cost you quite a bit.