Growbeds

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Growbeds in Aquaponics are where the plants grow.  There are several types of growbeds that can be used for Aquaponics but I will discuss the media or gravel filled growbeds generally used in flood and drain systems and the three major functions of such growbeds.

A growbed can be made from most any container of appropriate size so long as it can contain water.  Important factors in deciding what to use for growbeds include;

Will the container hold water?

Is it sturdy enough to hold water and gravel without breaking?

Is the material safe for the fish, the plants and the people eating them?

Will the material last out in the elements?

Can plumbing be attached to the container?

Is the container of a good size and depth?

Can the container be supported where in needs to be in relation to the rest of the system?

Grow beds can be made out of many things;

Feed or water troughs, plastic storage bins, plastic barrels, large pipes, fiberglass, big water tanks, kiddie pools, concrete tanks, and even wood or earth lined with pond liner.  (A quick note about galvanized containers, the zinc may be very bad for the fish so if used they should be coated with an appropriate material or lined in some way.)  Most metals other than stainless steel should probably be avoided where they will be in constant contact with the system water.

The size will depend on the system design but most people seem to agree that a growbed should generally be at least 1 foot (30 cm) deep.  This gives a good amount of surface area within the flood and drain range to provide good bio-filtration.  It also allows some depth for plant root growth.  The beds size for the other dimentions is usually bassed on how easily one can reach all the plants in a heavily planted bed (some where under a yard or a meter accross is usually plenty wide enough.)  The length will depend on system design and space available.

The bottom of a grow bed generally needs to be several inches higher from whatever it is draining into.  If draining into a tank or sump in the ground, then the growbeds only need to be a little above the top of that container.  If draining into a tank that is 3 feet high, then the grow beds need to be on stands or up the hill from such a tank.

The Three functions of a gravel or media filled flood and drain Growbed are;

1-provides surface area for bio-filtration

2-provides solids filtration

3-provides support for growing plants

Other methods may be able to provide these functions but only a gravel filled growbed provides them all in one single unit.