One of the cheapest and easiest hydroponics systems employs gravity to transport the water to and from your growing container. It is a basic system, sometimes referred to as the bucket system or flooding system. This system can be made from a bucket, a dishpan and a length of tubing. You can use perlite or gravel as your growing medium.
Select a plastic container, such as a dishpan, that is long with low sides and 3 to 4 inches tall. Clean it thoroughly.
Select a clean bucket that will hold at least 3 gallons of water. The bucket should be plastic, so you can cut a hole in it.
Cut a length of 3 to 4 feet of plastic tubing. The diameter of the tubing should be 1/2 to 1 inch.
Make a hole in the plastic container and one in the bucket. Make the hole in the plastic container on one of the short sides. The hole in the plastic container should be the same diameter as that of the plastic tubing. Cut the hole so it is 1/2 to 1 inch above the bottom of the container. Cut the hole in the side of the bucket the same size as the diameter of the tubing. Make this hole 1 to 2 inches from the bottom of the bucket.
Insert one end of the tubing into the hole in the bucket. Insert the other end of the tubing into the hole in the plastic container. Seal both ends with silicone or aquarium cement.
Place the plastic container on a tabletop. Fill with perlite or comparable growing medium. Place the bucket on a higher surface, such as a taller table next to the table with the plastic container.
Plant small seedlings in the growing medium. Slowly add water that has been enriched with appropriate nutrients to the plastic container until the growing medium is completely moistened.
Lower the bucket to the floor and allow the water to drain from the plastic container. This allows you to determine how much water is needed to process through the system. This will help you avoid flooding the container with too much water and dislodging your seedlings.
Once the water has completely drained, wait 2 to 3 hours. Raise the bucket and place it on the surface higher than the plastic container. The water will drain down into the plastic container from the bucket. When the water has completely drained from the bucket, lower the bucket and allow the water to drain back into the bucket.
Raise and lower the bucket two to three times a day; how often you need to flood your plants depends on your climate and how quickly your growing medium dries out. Add an additional cup or two of nutrient rich water to the bucket system once a week or as needed to maintain the amount needed to process through the system. Renew the water completely once a month.