Wicking beds

Wicking bed

Pipes arrangement	When arranging an array of wicking beds, I like a single outflow. The outflow leads water away from the plant-bed.  A screw-double-sided connector affixes the tub wall. The outflow hole (OH) is simply the perpendicular join of a T-connector. Thus the height level of the OH must be below inner drainage-pipe’s top face,  and the OH will designate the desired water-height inside the wicking bed. For 3 or morewicking-beds in sequence, having outflow holes   between each bed, rather than just one, may prevent the flooding of the furthest  bed.   Maths:  The height of the water-level inside the wicking bed,  is measured from the tabletop to the level. the height of the outflow hole needs to be the same height above the tabletop.
Tub	The Tub must fit the table comfortably, without being too skinny.  The tubs should be sturdy but beware of twisting and cracking a tub full of stuff, only attempt to move an empty tub.   If the tub plastic is so weak that it buckles out, try making two holes on either side at the top of the tub, and tighten a string between the two holes as a ‘strut’.  An ‘emergency’ excess-water hole should be placed half way above between the water level and the top of the dirt . Thanking God in prayer, we find a suitable bed. If plastic it should be food-safe and BPA-free. A rough approximate is that : half of the fish tank’s volume  = total growbed  volume (litres or gallons). in maths: fish_water (litres) = 2 x grow bed (litres)
Rocks (substrate)	The substrate is the important part of any Aquaponics vegetable grow-bed because it provides a home for the “Nitrifying bacteria” that cleans up the fish ammonia. BSA: Finding the Biological Surface Area (BSA) calculator which calculates the ‘home’ of the bacteria, will tell you that the finer the grade of pebbles the better your aquaponics will fare. You can try <a href=http://www.ecosia.org/search?q=Biological+surface+area+aquaponics+table> find the BSA tables for aquaponics</a>, as they improve over the decades. Small Pebbles not large rocks: That is because small pebbles has more surface area than large pebbles (for  the same weight.) Wash: If you use ‘unwashed roading gravel or pebbles, then make sure to wash the stones of dust which will contaminate the fish’s water.
Separator(geotextile)	The Separator keeps the rocks down and the soil up. Thus keeping the water free from mud. The separator ideally should let the water travel without dirt, which allows ‘wicking’ (osmosis) to occur. Some suggest Hessian sacks (sold second-hand by coffee grinders and cafes) but there is a purpose built material called “non-woven geotextile” which allows water to travel through and stops dirt from escaping. It is called  a geotextile because it promotes osmosis, which is what we need in a wicking bed. The geotextile wraps the dirt on all sides except the top.  non-woven Geotextile works out cheaper for me and better quality than importing ‘hessian’ sack. The Oblong sheet of material will fold in the corners to prevent dirt from escaping out the sides . Maths:  Cut out the oblong to have the following length and width. Tub’s Dirt_height = Tub_height – water_height . width = dirt_height + dirt_height +  Tub_width Length = dirt_height + dirt_height + tub_length.
Plant soil	The plant soil can be any soil, preferably old compost mixed with top-soil.  Simple “Potting mix” would do nicely. Bearing in mind not to fertilize the ground at all, or not with poisons, as the fish and fish-food provide the fertilizer.  The idea of not using soil here, means having to remove the separator and thus, requiring a bell-siphon system instead.
Drainage pipe	Here, is where the outflow hole is carefully positioned to be not heigher than the  water-level’s drainage pipe’s upper surface. The drainage pipe should have many holes at the top vertice of the pipe. It may seem easier to have one pipe sticking straight up, with a single hole  at the water-level, but, infact that one hole is small. So a horizontal pipe, that can stretch the length of the tub, will provide adequate drainage, so long as the top of the pipe where the water reaches, has enough holes. The picture below, shows the pipe and it’s holes.
Rain protection device.	Making an A-frame out of galvanized wire. And threading the clear plastic sheet through the wire, provides protection from the rain. If the rain gets into the wicking bed, then the bed will get flooded, and mud will run into the fish-tank (very dirty water). a continuous sheet of plastic, which is threaded  into place by the wire-frame, with an slight overhang  off of the tub’s lips, will let the rain water drain away from the dirt. having multiple small-widthed strips of wired plastic coverings that span the entire width of the tub works well to let the plants grow tall and keep the soil dry from rain. See the picture below.