I've done powdered Spirulina, never done Chlorella but I've heard amazing things about it first-hand. My neighbour has been taking it for years which was surprising to me because he isn't exactly a health nut but for some reason he got on it years ago and never stopped. His are by the company SUN. Apparently they are the best in the business ( and a bit pricey ), but he says it's well worth the money. He's a drinker and whatever else and he always attributes his tolerance and fast recovery to Chlorella.