Superthrive is a lot less expensive. A 1 oz. bottle of Superthrive is about $7.00 and according to the instructions, you [FONT="]only need 1 drop per gallon. I haven't tried Superthrive but am considering giving it a shot in my Aerogarden. I've heard a lot of good things about H&G Roots Excelurator but it's a little pricey.
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