Aquaponics: How a Bell Valve Works

A bell valve is used as an auto siphon for a home aquaponics system. The mechanism of auto-siphoning is used in aquaponics to control the flood and drain cycles in the growbed, where the plants are grown.

What is a Siphon?

If you wish to draw water from a higher container to a lower one, a siphon may be used. Auto-siphon is a mechanism that works on its own, without you having to draw water manually. A bell valve is used in many aquaponic systems as an auto-siphon.

Bell Valve Composition

A typical bell valve auto-siphon system has a tall standpipe that’s vertically placed inside the growbed. This extends through to the base of the grow bed. It also has a freestanding siphon pipe which is placed over the standpipe. This pipe is taller than the vertical standpipe and one end is fitted with an end cap. A hole is made in the end cap to fit the air tube. The base of this pipe has pieces that are cut out, to enable water to flow freely. The bell valve also features an air tube to help break the siphon, when there’s a drop in the water level. This is placed on the upper part of the horizontal end of siphon, on the hole that’s cut out for this purpose.

Mechanism of the Bell Valve Siphon

When the growbed of the aquaponic system is flooded, water raises and flows between the walls of both the pipes. Then, the water flows inside the stand pipe and creates a siphon. The water that is trapped in the siphon pipe should fall back to the growbed. Air is required to break this siphon and the air tube provides this break. Once the siphon is broken, the water falls back into the growbed. When the level of the water is below the air tube, air gets sucked in. This air will move along with the flow of water, till the water level of the growbed falls and is below the end pipe of the siphon. Although this stops the flow of water into the siphon, air continues to get sucked in through the air tube. Subsequently, the siphon gets filled with air and breaks the seal. For the mechanism to work well, it would be best to place the air tube at a height of about 12mm above the lowest height level of the siphon pipe.

Maintaining the System

For the bell valve siphon system to work well, you should ensure that the water from the growbed flows into the pipes easily. You should also ensure that the ends of the pipes don't get clogged and are thus free for the smooth flow of water.

It is in this way that the bell valve auto siphon, controls the flooding and draining of an aquaponics system. Many home aquaponics enthusiasts prefer to use the bell valve as an auto-siphon for homes, because it is easy to construct and maintain.