This is the largest tub Sun Chlorella make, and it exists because the recommended serving is unusually high.The tablets are 95.5% pulverised chlorella with 4.5% sunflower lecithin, and nothing else. Sun Chlorella pulverise the cell wall rather than cracking it, which is their long-standing point of difference: chlorella's cell wall is indigestible, so how a producer breaks it down determines how much of the contents you can actually use.Their directions are to start at five tablets a day and build gradually to a serving of fifteen to forty, taken all at once or spread through the day. Building up slowly matters here, as chlorella can be uncomfortable if you begin at the full amount.At fifteen tablets a day this tub lasts about three months; at forty, closer to five weeks. That is the arithmetic that makes the 1500 size worth its price against the 300.A food supplement is not a substitute for a varied diet.