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American Hydroponics Companion Biological Fungicide is a highly concentrated liquid Bacillus subtilis (GB03) designed to maintain a disease-free system. Whether you are an established greenhouse grower, a hydroponic hobbyist, a tried and true soil grower, or fall somewhere in between, keeping your plants healthy at all growth stages is a key to success.

Each ounce of this 100% natural liquid contains a staggering 43 million beneficial Bacillus subtilis GB03 bacteria. Once they “set up shop,” these amazing microorganisms also help reduce transplant shock, stimulate root growth, and make nutrients more available for plant uptake.

• Fights a broad range of disease
• Can be used from seed to harvest
• Increases crop yield
• Highly concentrated, little is needed to make a big difference
• Produces a more vigorous root system
• Injects through even the smallest tubing with no clogging
• Compatible with all fertilizer programs, even other beneficial bacterias!

Available in quart (32 oz) sizes.


Hydroponics: Mix 1 ounce per 30 gallons, every 2 weeks (or at each reservoir change)

Soil: Apply 2 teaspoons per gallon, every 2-3 weeks

Foliar Spray: Use 2 teaspoons per quart, every 7 days

Product Data Sheet (PDF)

Grower’s Tip:
No matter where you are in the growing cycle, it is critical to keep your plants their healthiest. Besides looking better, healthy plants are more able to take up and utilize critical nutrients. Your plants will be stronger and more able to resist pests, disease and other stresses.