Installing DWC unit

The plan is to assemble the DWC frame built earlier, then lay out tarpaulin as base layer followed by pond liner.

First DWC unit. The frames are assembled using metal corner bracket. Hole for water return to sump tank was drilled prior to this.
Second unit, about 1 feet apart from the first one.
The space between these units became narrower when all 3 are completed. Here I measure and cut the 2-inch UPVC pipe for dry-fitting, before putting on the tarpaulin.
The next day, laying out tarpaulin on the unit. The tarps are secured to the unit by using thumbtacks.
Second unit in progress, I had to work quickly since rain is coming.
Done laying out all three units, seems I don’t have enough time to lay out the pond liner, so I just connect the pipe, and wait for the rain to come down. From my observation, around one hour of heavy rain, the unit only filled about 1 inch deep.
Later that night, I put the styrofoam board in. It’s important to evenly lay out the tarpaulin, because the board might not fit as shown above. Minor adjustment to the tarp and let the unit filled with more water allow the board to settle floating on the water.

Setup fish tank solid lifting overflow

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.

Holes at the bottom of the standpipe.
Standpipe height determines the water level inside the fish tank.

Building trickling bio filter

Trickle filter design

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.

Using ½ inch PVC, cut into half, I tied it onto 4 sides the pail to create holder for the colander, to prevent it from tumbling inside the pail.
Underneath this K1 bio media is the clay pebbles. By right it should fill about half of the pail capacity. This bio filter tank doesn’t need to hold water so the outlet to the sump is located near the bottom.

Building radial flow filter

Design of the radial flow filter

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.

Inside of the filter.
This is how it looks like from outside.
For the standpipe, I recycled cooking oil bottle and tied it to the lid of the pail.

DWC frame

This is how I build the frame for the deep water culture (DWC) unit for my aquaponics system.

This is the initial plan for the DWC frame. Pond liner will be laid inside the frame to hold water for the hydroponic component of the system.
Measuring out the woods to be cut. The styrofoam board is 2 by 4 feet, and I add 1 inch to the frame width & length to give more room for adjustment and to prevent the board from fitting too tightly.
Planing the woods, this will give smoother surface for varnishing later. These wood dust would go to our composting box.
The standing part of the frame, 36 of them.
Left aside for the varnish to dry. I choose to varnish them to prevent it from rotting quickly due to rain and termite. I plan to reuse it when we moved to our own village house in the future.

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.

These are for the 4-foot frame width part.
And these are the 12-foot frame length, already planed and going to be varnished next.
After planed, varnished, re-measured and re-cut, these woods are joined together using 1½ inch tapping screws. I drilled the holes for the screws first so that it can be fitted without breaking the wood.

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.