How to Use Pumps to Make Compost Tea

You need a bucket and basic aquarium supplies to make compost tea.

Proper aeration is essential for making compost tea. Without aeration, harmful anaerobic bacteria take over and the tea is nothing more than dirty, stagnant water. Keep air flowing through the water during the brewing process and you will have an all-natural fertilizer instead. Compost tea provides nutrients and also helps prevent many soil-borne diseases when used as a leaf spray or as a ground soak. You do not need a high-tech pumping system. An aquarium pump and some air stones will provide all the aeration you need to encourage the right bacteria and microorganisms to thrive in your compost tea.

Things You'll Need

• 2 5-gallon buckets
• Medium aquarium or pond pump
• Extension cord (optional)
• Several feet of 1/2-inch plastic tubing
• Scissors or a sharp knife
• Gang valve
• 3 air stones or bubblers
• Mature compost
• Hose and water source
• 1 ounce organic unsulfered molasses
• Stick
• Old pillowcase

Instructions

1. Set up your materials in a location where they will be undisturbed for three days. It is helpful to have an outlet nearby, otherwise you will have to run an extension cord across your yard.

2. Place the pump near one of the buckets. Clip the gang valve to the rim of the bucket. Cut a piece of tubing long enough to reach from the pump to the gang valve and connect it to the pump and gang valve.

3. Cut three lengths of tubing long enough to reach from the gang valve to the inside bottom of the bucket. Connect these lengths of tubing to the gang valve. Push an air stone onto the loose end of each piece of tubing. The air stones should rest on the bottom of the bucket.

4. Fill the bucket with water. Turn on the pump and let the air stones bubble for an hour. This will remove any chlorine present in the water. Many municipal water supplies have chlorine added to kill pathogens, but that chlorine will also kill the beneficial microorganisms you want in your compost tea.

5. Fill the second bucket halfway with mature compost. After the water has aerated for an hour, pour enough over the compost to fill the bucket to within 3 inches of the rim. Stir with a stick to mix well.

6. Disconnect the gang valve from the water bucket and connect it to the compost bucket. Bury the air stones in the compost so they rest on the bottom of the bucket.

7. Turn on the pump and let the air stones bubble for a few minutes. Pour in 1 ounce of organic unsulfured molasses and stir vigorously. Rebury the air stones.

8. Let this mixture sit and aerate for three days. Give it a vigorous stir several times per day. Remember to bury the air stones after stirring.

9. Place an old pillowcase inside the empty bucket. Fold the edges over the rim. When the compost tea is ready, pour it into the pillowcase to strain out the solids. Use the compost tea immediately.

10. The used compost can be returned to the compost pile or spread directly on the garden. It still has enough nutrients to be helpful as a soil amendment.

Tips & Warnings

• Make sure to cut the tubing long enough to reach from the pump to the gang valve, and the gang valve to the air stones, without stretching. If the tubing just fits, it could come loose and you will lose aeration.

• Make sure the air stones run continuously for three days. If the water is allowed to sit without aeration, it will become stagnant as anaerobic bacteria take over and kill off the beneficial bacteria.

References

• Oregon State Extension Service: Aerated Compost Tea
• BioCycle: Brewing Up Solutions to Pest Problems

Resources

• Fine Gardening: Brewing Compost Tea