The Black Box

This is the second translation in a series of articles regarding hydroponics. For the original post, check out my friend Martín’s website, Hidroponía Casera, here!

The Black Box! The hydroponic system for less than 20 Euros.

Hey there!

I just finished making a system to cultivate my plants, on the cheap, too! We’re going to make a simple and effective hydroponic system, spending only 20 euros.

The Black Box. A hydroponic system using a container. We need:

  • 1 Plastic box (4 €)
  • Black spray paint (2 €, optional, depends if your box is see-through or not)
  • Sealing tape (optional)
  • Air pump
  • Tube and bubbler for the pump ( 3€)
  • Plastic cups or baskets for the substrate (0.75 €)
  • Drill

Total: 19.75 €

1. Paint the container if it’s not opaque

The Painted Box

My box was transparent, so I had to paint to keep light from getting in to prevent algae from growing in the hydroponic solution. You can use other colors , black will block out light the best, but it can overheat if the box is in the sun. A better idea might be to give it a black coat and then white over top. Before you do this it’s a good idea to  place some sealing tape on the side of the box from top to bottom, after we paint it we’ll take it off and we’ll be able to see the level of the solution inside without having to open the lid. Convenience over everything, you know!

Box with an opening to check the liquid level

2. Make holes for the baskets with a drill

Make sure the diameter of the holes is the correct size. A recommendation from this rookie handyman, don’t drill while the lid is on the box, the lack of support in the middle combined with the vibrations almost broke my lid in half (in some of the pictures you’ll see a significant break). My solution was to drill on top of gardening soil, the top gets a little dirty, but the result is acceptable.

I also tried to follow some recommendations that I found saying to use metal cookie cutters. The idea is to heat them up until they’re hot enough to melt the plastic. It ended up being slower, more complicated and the metal didn’t heat up enough to melt the lid, so lesson learned. I’ve also read that melting it with a soldering iron works as well.

The cuts aren’t very clean, but we’ll hide them later

3. Make a hole for the water pump

This box sure won’t win any beauty contests

4. Insert the tube, the bubbler, and the baskets, and you’re done!

Now we can use this system for our hydroponic crops. We can fill the baskets with our favorite grow media and any plants we like. Ideally, the seeds will be germinated in a seed bed until they grow roots, then we’ll move them over to the containers. Remember to pay attention to the level of nutrients in the media so your plants don’t get hungry.

Here’s the side view

View from the side


I’ve gotten some questions about the system, so I decided to clarify a few things. The cups in the image are plastic, if you don’t have plastic baskets on hand (you can buy some easily). I used plastic cups with holes in the bottom. You’ll have to drill holes in the bottom to turn them into baskets.

Here’s a photo of another version of the same system with plants. Now onto the frequently asked questions.

How much water does it need?

I had, I think, around 8 liters for 6 plants. In my opinion that’s small, because when the plants got bigger, I had to change it often because of the lack of nutrients and the pH wasn’t that stable either. The bigger the better.

How strong does the air pump have to be?

Like I said before, the more aeration, the better. In my case, I didn’t use a water pump, since the system was in my room and I couldn’t sleep because of the noise, but as you can see, the plants grew relatively big anyway (actually, they grew much more, in these photos I’d taken off a lot of the basil and mint leaves because there wasn’t any room.

Black box with young plants
Black box with adult plants

Now you have no excuse not to tinker with hydroponics at home! I hope that this has been useful to you, and if you want to put your friends to work, you know what to do, share!