Performance Characteristics of Siphon Outlets

Siphon Size

• According to biotechnologists at the University of Hawaii, the diameter of the pipe used for the bell siphon should be twice the diameter of the standpipe inside it -- sometimes called the "drain pipe." If the siphon pipe is 1 inch wide, the standpipe should be 1/2 inch in diameter. The size of both pipes depends on both the size of the grow bed and the size of the fish tank. Proportional representation is key to success in aquaponics.

Snorkel Tube Size

• Air enters the "snorkel" tube when a grow bed is drained, and the entire bell siphon cycle begins again. Therefore, snorkel tubing has the smallest diameter in a bell siphon system. Practitioners use vinyl tubing for grow beds of up to 32 square feet. If your dimensions are larger, use PVC pipe. The snorkel tube must be three-sixteenths of the bell pipe, or outside diameter (OD), and one-eighth of the standpipe, or inside diameter (ID). The equation is: 1/8 OD x 3/16 ID.

Grow Bed Size

• Grow bed dimensions combine width, height and depth -- L x W x D. A siphon with a 1 inch bell pipe is sufficient for a grow bed of 1 foot long, 4 feet wide, and 1 foot deep, or 1 x 4 x 1. This covers 4 square feet to the third power, or cubed. A 2-inch bell pipe feeds 16 square feet, or cubed, of grow bed. The bigger the pipe, the more water will flow into the grow bed at a faster rate.

Aquarium Size

• This is where aquaponics gets tricky. The appropriate aquarium size depends not only on siphon pipe size, but also on your intentions for the fish. Some people grow fish for food, while others use outdoor ponds containing decorative fish. Of course, healthy aquatic habitat is influenced by the size of the fish themselves and how many can fit comfortably in any tank area. Be aware that problems with fish health may have more to do with aquatic habitat than siphon pipe performance.