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From:
GENERAL HYDROPONICS
WHEN IS KOOLBLOOM BEST USED? HOW MUCH?
Answer: KoolBloom can safely be used three to four weeks before the end of the plants life cycle. Use only the recommended dose of 1/4 tsp per gallon (1.5 g / gallon). This will increase the ppm by approximately 200 ppm (0.4 mS).