Aquaponics germination station

In this post I’m going to go through the process of building my aquaponics germination station, materials used and shop where I got them from.

I’m using 5-level metal boltless rack for this germination station, aquarium size 1x2x1 ft (WxLxH), and two car boot tray (15×32 inch) which surprisingly all of them fit well.

I bought this rack from DC Rack at Jalan Green. They have variety of racks at reasonable price, so it’s highly recommended.

For the outlet at the car boot tray which acts as the grow bed, I’m using ½ inch HDPE tank connector, fitted with ½ inch to 16mm connector. For the hole, I drilled it using 22mm hole saw.
Here’s the connection from the top grow bed to the below one, using 16mm HDPE pipe. At first I connected them directly without elbow, but the pipe bends and disturb the water flow, and also it look messy.
Here’s the line from the water pump inside the aquarium, with ball valve to control the water flow. I put some cloth there as a mechanical filter, and some clay pebbles or hydroton below which act as biofilter, where it provides surface area for nitrifying bacteria to colonize.

Ball valve is extremely important here to control the water flow. I have to match the flow rate of water that coming into the grow bed, which is under pressure, with the flow rate of water that coming out, which is by gravity. If the water coming in is more than the water that coming out, the grow bed may be flooded and water level in aquarium may dry out.

On the other hand, the outlet pipe should be clear of any debris as it might slow down the water flow, which again may cause the grow bed to flood, as it only depends on gravity.

All of the 16mm elbow, tee and connector I use here were bought from Garden Hobbies Collection near Emart Matang, while the tank connector I got from SK Hardware, and the pipe was ordered online, but it also can be bought from the gardening store mentioned earlier.

Water pump I use is a 20W, 1500L/h with 1.6m head, and it has a matching 16mm outlet, which I got it online. It sucks water from the bottom, so it’s useful to clean up the fish poop at the bottom of the aquarium. The fish we have here is shubunkin goldfish, 15 of them, but we also have ikan puyu (climbing perch) below there, which we have initially, but it can’t be mixed with the shubunkins because it might eat them.
Germination station now installed with T8 LED grow lights (2 ft long), one for each level. The light has to be at least 30cm from the plants below, thankfully by using boltless rack it’s easier to adjust the rack levels.

I bought these grow light online, and for those who plan to buy them, make sure it matches your electricity voltage and current type. This grow light supports 85-265V AC (alternate current), and here we have 240V, so it matches. If the product stated DC (direct current), it only support electricity from batteries or solar panel, or you need to use adapter (to convert AC to DC) if you want to connect with your home electricity system.

This LED grow light emits blue and red colour lights, essential lightwave for plants to perform photosynthesis. Alternative to this, is by using regular light bulb, but by mixing the cool day light and warm light, to provide the full light spectrum needed by plants.

Here’s the electrical part. I’m using 3-plug extension wire, to connect the grow light, aerator and water pump. I put a timer on the grow light, set it to turn on from 6.30am to 6.30pm, while pump and aerator are switched on all the time. The aerator has to be suspended over a rope as shown above to reduce the vibration noise. Similarly, the air stone shouldn’t sit on the aquarium base as the vibration will produce more noise.

Aerator is needed in this setup to provide extra dissolved oxygen, not only for the fish but also for the water that get pumped up to the grow bed, to prevent root rot. There’s also another LED light above the aquarium, which we turn on only at night, and it provides nice view of the fishes inside the aquarium.

Sowing method shown here is using sponge cube, cut in half so that seeds will be clamped inside when fitted into the germination tray. This is to make it easier to take out the seedlings during transplanting later. This method is suitable for leafy greens.

Another method is using cocopeat – spray it with water to wet it a bit, then fill it into the germination tray with larger hole, poke a tiny hole at the cocopeat then put seeds in there. This method is more suitable to larger type of plants, which take longer time to germinate & have larger root system.

This is cili geronong, after one week sowed using cocopeat, now already starting to germinate. Problem with using cocopeat is that it cause the water inside aquarium to turn cloudy and dirty.
The blue sponges are pak choy while the green ones are sawi putih (white stem choy sum), also after a week. At back there I change the filter with coffee strainer, which work quite well, except that it doesn’t allow high water flow rate and sometimes it overflow from the opening of the strainer.

We cover the grow bed area with cloth because the glare from the grow light is unpleasant to our eyes, and since this germination station located in the living room, we’ll see it often as we pass by and we want to reduce this disturbance. This cloth also need to be held together using paper clip because when there’s wind coming in, the cloth might flapping around and land on the grow bed or in the water.

To check the water quality, I’m using this ammonia tester. I try to keep the ammonia level below 2.0 ppm, and if the level stay high, I’ll change the water. Murky water caused by the cocopeat doesn’t affect the fish much, but if causing problem like the fish can’t see its food, then I’ll do a water change too.

I don’t have the full test kit, so I can’t verify if the system is already cycled – by checking for presence of nitrite and nitrate. It’s already been around more than two weeks, based on online reference, it may take up to 2 months for the system to be fully cycled.

So far, the routine we have done is to feed the fish 3 to 4 times daily, each time with a pinch of feed. And every day I’ll take the ammonia level reading, and if the level stays at 2.0 ppm for two days, then on the third day I’ll do a water change. Note also that I use harvested rainwater for the water inside this system. Other than that, we don’t have to worry much about the plants as they grow by itself with enough light, water and nutrient.

Scaling down aquaponics set

Since last update about aquaponics, where I faced problem with leaks, I tried to scale down the aquaponics set from 1000 liters of fish tank and 3 DWCs, down to where it’s financially practical for me to run it. Because to run at that capacity, I figured the budget for the fish feeds, electricity, water supply and various maintenance cost might be overwhelming when I still don’t have proper channel to sell the produces.

DWC was reduced to one bed only.

I changed the piping to use 1 inch PVC pipe because it’s easier to find the tank connector of that size, which helps prevent leaking. I also drilled another hole at the fish tank, which is lower than the first one, to reduce the amount of water and the fish which going to be grown here.

Solid filter and bio filter were changed to 5 gallon buckets. Note the drain pipe for the radial flow filter is directed outside of the sump tank, to simplify the sump tank layout.
Water from sump tank was changed to pump directly to fish tank, without any split flow, so that the high water flow will help create circular flow inside the fish tank.
Unfortunately, that didn’t work really well. This tank has bump on the its base, so the solid are stuck between those bumps which prevent solid lifting overflow to work.
And for the bio filter, 5 gallon bucket is too small, and since the K1 bio media are floating, they are blocking the pipe outlet and cause water flow to jam – water pumped into fish tank are more than water that returning to the sump tank.

Since there were too many problems with the current setup, and I ran out of my budget and time to experiment, I decided to further scale down the system, to something that more controllable, like this:

Indoor aquaponics germination station.

To be continued.

Install water pump and test run

It’s time to install the water pump, do the wiring, fill water into the tanks and do a test run to check for the aquaponics system operation.

Using tap water, filling this 1000 liters tank took around 1 hour plus
This 2000L/hour submersible water pump is connected using PVC pipe to the rest of the system.
Using leftover plywood and planks, I made this sort of electrical box, which is then covered with tarpaulin, to house the extension plug from rain.
Here’s the finished box, where I put also the timer for external lighting.
Water pump is installed inside the sump tank. Got some leaking at the connection, I used PVC male socket, layered with 15mm hose (orange color) and then clamped with the 1-inch connector hose (transparent).
Filling up the 3 DWCs. The water flow quite low here, even with the valve to the fish tank is closed. Maybe because of the leaking at the connection inside sump tank. It took a lot longer to fill the DWC to the desired deep (1 feet), so I just fill up to the stand pipe height (around 4-5 inch).
As the water inside the DWC rises it became apparent that it got some leaking. However, with the current design of the DWC, it’s quite hard to detect where the leaking is, because I can’t lift up the DWC and check underneath.
Among all of the causes of leaking, I think this is my biggest mistake. Silicon sealant doesn’t work on pipe connection, and it is harder to do adjustment because I need to wait for the silicon to dry. When the water inside tank rises even for a few inches, it creates water pressure which silicon sealant cannot contain.
So I disassembled two of the DWC and try to work with only one in fixing the leaking issue.

Currently I hit a roadblock in building this aquaponics set. First is the leaking issue. It’s like everywhere is leaking, due to my usage of silicon sealant at the pipe connection. I decided to use sealant because I couldn’t find suitable pipe fittings for the tanks:

  • there are no uniseal sold here, even the regular rubber seal only have size up to 1.5 inch.
  • bulkhead fitting is quite expensive, and I only can find it sold online
  • 2-inch PVC tank connector doesn’t fit with 2-inch UPVC

Another issue is the low water flow from the water pump. This probably cause by the leaking at the sump tank connection, and also maybe because of the head height (2 meters). Water from the pump is split to the fish tank and DWC. Pipe into the fish tank is around 90 cm height, so assuming the flow rate decrease is linear, at 0.9 meter, the water flow is theoretically 1100L/hour. Adding the split line to the DWC and all the elbows turn that add friction to the water flow, the value might be much lower. For now, I let the valve at the DWC slightly open and at the fish tank fully open, but only little flow is coming out to the fish tank.

Plumbing the aquaponics units together

Revised plan.

I changed the arrangement of the tanks, and solid filter drain outlet now connected directly to the sump tank, to reuse the water while filtering out the solid waste.

Overview of the arrangement of fish tank, then to solid filter, and then bio filter, and lastly to the sump tank in the ground.
Inside the sump tank. All water returns here, except for pipe from pump, which distributes back the water to the fish tank and DWC, and the overflow pipe (at 6 o’clock)
Pipe into the fish tank, with ball valve to control the water flow. It’s about 3 ft. (90 cm) in height.
Pipes to the DWC with ball valve each, and about 16 in. (40 cm) height.
And these are the stand pipes from the DWC back to the sump tank.

All pipe connections are glued, and the connection to the tanks are sealed using silicon sealant. This is far from complete, as I still need to do test run & check for any leaking. Also need to make sure correct water flow from the sump to the fish tank and DWC.

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.