The plan is to assemble the DWC frame built earlier, then lay out tarpaulin as base layer followed by pond liner.
Solid lifting overflow is designed to automatically clean the fish tank from solid waste by using circular water flow, which gather the waste at the center of the tank, then the standpipe will suck the solid out to the filter tanks.
At the bottom of the standpipe (see A), there are small holes for the water to flow and to prevent fish from entering it. When the water overflow at B, it will create small siphoning effect at A which carry the solid out of the fish tank. T connector is used at the standpipe to prevent full siphon effect from occurring which will drain the fish tank completely.
Bio filter provides extra biological surface area for nitrifying bacteria to convert ammonia into nitrite and then nitrate. Trickle filter works by dropping water from fish tank through some kind of trickler (see A in diagram above) onto bio media (see B) and bacteria living on these bio media will help the nitrification process. Trickle filter also helps in degassing process, when the water trickle down, it contact with the air and some gas inside the water will be released to the air, such as carbon dioxide and excess nitrogen.
I use colander to create the trickle effect. This colander will be covered with some cloth, which function to filter out fine solid that escape the radial flow filter. Bio media that I use is K1 bio media, however I only have 1kg of them, which occupies about 6 liters of volume, so I added together some clay pebbles I have around to increase the bio media volume. Both media are wrapped inside a mesh cloth.
Radial flow filter is used to remove large solid waste from fish tank. The way it works is by directing the flow upward (see A in diagram above), and a standpipe to direct the flow downward, forcing the large solid to settle on the bottom of the tank. Outlet to the bio filter is positioned higher to avoid the solid to exit the filter.
One addition for this tank is I add an outlet (see B) with a ball valve to drain the tank including the waste out of the system. This drain pipe will connect to the sump tank to reuse the water, while I can use either mesh bag or cloth to collect the waste and put it into the mineralization tank
Using 50mm (2 inch) hole saw, I drilled two holes on the sides of a 12 gallon pail for the piping from fish tank and to the bio filter. While for the drain pipe, I used 22mm (½ inch) hole saw.
This is how I build the frame for the deep water culture (DWC) unit for my aquaponics system.
One thing I learned when working with varnish is I need a lot of thinner to dilute the varnish. The way I do it is by pouring some varnish into paint tray, mixed with some thinner, and paint a thin layer on the wood. However thinner evaporate quickly and the varnish eventually become thicker again, so I have to regularly add thinner to the varnish.
Not an easy task to do, some of the wood are bending so need to use more force to screw at the right place. Some are hard wood, so when I drilled it continuously, the drill bit become too hot and break eventually. If I use small drill bit size, it’s harder to screw, and some screws couldn’t go in, I had to cut them and replace with nails.