Small Aquaponic Unit





Introduction: Small Aquaponic Unit

About: Short fat and bald. Have three boys. Also cub leader and a computer programmer.

I am about to get heavily into Aquaponics and thought I would start with a simple unit just to test things out.

Aquaponics: is the symbiotic cultivation of plants and aquatic animals in a recirculating environment. Alternate definition: An integrated hydroponics (growing plants in water) and aquaculture (growing fish) system.

Aquaponic systems can be small like this one or large commercial setups. I have found and invaluable source of information.

This system is very simple. Basically I put a box on top of my fish tank and pushed the pump through it and added some holes rocks and plants.

Step 1: The Grow Bed

The Grow Bed is where the plants will grow. The grow bed medium can be anything that will support the plants. I used fine rocks but blue metal and so on is ok. Just clean it first.

In this example I have used an old plastic storage box. I drilled two large holes on one side.

1 For the Pump to go through
1 as an over flow valve in case drain holes fail.

Along the one side I drilled a series of holes to drain the water back to the tank.

Then simply placed the container on top of the tank at an angle to allow the drain holes to be flow back into tank and the pump and over flow to be near the top. (Look at side view)

The pump I am using is the standard pump that came with the tank. Any pump will do just needs to pump water from tank to the grow bed.

After washing the grow medium I place it in the grow bed.

Now I let the system run to ensure it doesn't over flow and look for any issues.

Step 2: Plants

Aquaponics will grow almost anything you just need to add the plants to grow bed and sit back and wait.

In this case I planted some Lettuce along the top (Close together but will thin out latter) and some watermelon seeds along the bottom.

Plants will grow quickly in aquaponic systems.

The plants clean the water for the fish and the fish dirty the water for the plants. What a great cycle :-) The chemistry of it can be found on almost all Aquaponics web sites so type the word into google ( ) and learn more. This would be a fun Classroom experiment and an example of natural cycles.

Step 3: Fish

Here I am using gold fish. For a fish tank that is perfect. When I build my big system I will be using trout or a similar cold weather fish. I will be eating those fish as they get bigger but my kids wont let me eat the gold fish.

Other aquaponic systems have anything from Yabbies (small fresh water crustatian) to large eating fish I have even heard of a salt water systems.

Step 4: Completed

The system is completed. All I need do is sit back and watch. Check the water every now and again. Make sure the drain holes don't block.

My pump stops pumping once it is exposed to the air and since it is just below the water surface if a block does occur it wont result in much water on the carpet. I would suggest you think about the possibility of an over flow.

I will report back on the growth of the plant in this system.



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42 Discussions

I am not a huge fan of gardening as I know the amount of work you would need to put in every day in order to sustain a healthy system. However, I have heard of aquaponics which can be done indoors in comfort. I think I might give this hobby a shot and see how it goes as it does seem pretty interesting. Nevertheless, should you ever need to move out in the future, you would need to perform the necessary before you move into your new home to ensure the plants remain healthy throughout the phase.

need more pictures. Plastic is clear a can notsee where the holes should be and the level of the over flow.

FIY, Aquaponics HQ changed names about a year ago to One of my favorite aquaponics sites to this day, but I wish they would have kept the old name. I liked it better.

This is awesome. I am going to use this idea for my homeschoolers. Did you start with seeds or did you grow the plant in soil first and then transplant them?

A system which requires minimal space and at the same time very effective and convenient. Great job. Additional details about this system can be found on the link below.

A system which requires minimal space and at the same time very effective and convenient. Great job. Additional details about this system can be found on the link below.

Just wondering (new to aquaponics) - how do you feed the fish? Do you lift the grow bed out?

1 reply

you feed them until the plants grow strong enough to have the fish eat the roots.

Well all didn't go well. Seems I chose wrong plant as lettuce doesn't like wet roots. Also I couldn't control flow of pump so the box had too much water in it. I will add more holes and try another plant. By the way how many liters do you think the tanks is? Oh I don't use imperial measurements.

5 replies

Lettuce is about the only plant that one can grow floating on top of the water with its roots submerged as long as you keep the water aerated. So I guess that ineed you may wanna use an airstone

Im sure you have done a lot of research by now, but all you need was more oxygen in the water.

I'm by no means a hydroponics expert, but I thought it might be helpful to pass along something I've learned with my own water culture hydroponic system. If you don't have an airstone to keep the water aerated (which you normally wouldn't if you are keeping goldfish), then you need to make sure the roots get oxygen in some other way. The best way would be to make sure that the roots have some 'air' space in the grow medium before they get to the nutrient-rich water. Since you don't have a flow gauge on your pump you have to make more holes in the box (only at one end, which I'm sure you knew anyway). There comes a point when you can only make so many holes though. If you reach a point where you can't really add more holes without compromising the support of the box, then you need to add more grow medium to the box. That way the plants sit up higher above the water then previously. That will give the plant the options it needs to grow out instead of down. And you will end up with less waterlogged roots. Hope this helps. You may also want to do some research on growing lettuce as well. I didn't know that lettuce will 'bolt' if it becomes too warm. That means your lettuce can go straight into the flowering phase before it really does it's vegetative (bunchy leaves) stage. In my ignorance, I kept a cold weather plant (lettuce) under too much light in a hot spot and had to deal with lettuce that grew more like a vine than a head of lettuce. I ended up throwing the whole thing out because once it starts 'bolting' it won't stop which can be a real disappointment when you are looking forward to eating your reward. Hope this info helps.

From what I have read you need to have a cycle on the pump so the roots are not flooded all the time, unless you are heavily oxygenating the water as with an airstone on your air pump.

Trout are very fussy about water quality, rainbow trout are less so then brown trout though. You could try Perch as they are not as fussy about water quality and are quite tasty.In addition perch do not require as much water as trout and are not as territorial as trout.

1 reply

I know a couple that has an entire aquarium with a 7-foot tank beneath it. They raise tilapia. Not a picky fish - expensive to get started though.

What type of filter system is in the tank? I would suspect an under gravel since you want the fish waste to feed the plants but I wanted to make sure. If so are you removing the pump screens so that detritus is being pumped to plant bed. Also have you had any problems with over feeding plants or ending with excessive nutrients in the plant bed. This looks like a perfect scenario for celery or even wasabi root.

I have a question really. Were you or have you been successful growing watermelon in-doors with this type of setup? I am very interested in this type of "farming". I have a couple tanks not being used now and this seems to be a fun project for kids to learn a new possibly marketable skill.

When did you put ze plants in? When zey have had leavez? Or when they were lil' zeedz?