Wall Mounted Hydroponics (In Progress)

 Wall Mounted Hydroponics

 

 

For Christmas this year, my wife wanted me to build her an indoor hydroponics system. During the summer months we always plant a garden, even if it's small. We love the fresh vegetables and herbs, and it adds a really nice ambiance to our backyard. But when winter comes, and we have to give all that up, we struggle through without fresh mint. It's probably the hardest part of winter. Though, I do hear a lot of complaining about the cold...

When she mentioned the idea of building one of these, I was immediately interested. There is something special about combining digital control with fluid handling, to grow plants inside. And if there is one thing I can't pass up, it's the opportunity to significantly over complicate the process of obtaining tomatoes and basil. 

My hydroponics system is a combination of nutrient film technique, and ebb and flow. Using PVC for the main structure, and nylon tubing to pass the nutrient around.

Netcup Standoff

From the outset, I wanted to incorporate 3D printing somehow. I own three 3D printers after all, so I'm going to have to incorporate those into every project from now on I think... To that end, I came up with what I think is a fairly clever use.

Plants are grown in some sort of growing medium, held by a plastic net cup (black, in the below picture). It's very important for there to be some space between the top of the water, and the top of the roots, to allow them some room to breathe. Since they normally can extract oxygen from the moist dirt, it's very possible to drown a plant if the roots are constantly and fully submerged. 

So, to keep the net cup out of whatever water sits in the pipe, I designed these standoffs. They hold the netcups a few inches above the water, and the plants roots will eventually reach down to access the nutrient.

In this picture, you'll see two different sizes of standoffs. As I mentioned before, it's a combination NFT and ebb and flow - for very young plants that don't yet have long roots, you can place them in the short standoffs and when the pump runs to replenish the nutrients, it soaks the growing medium of the shorter ones. (At the moment I have the pump running once per day.... I don't honestly know what a proper cycle should be yet)

 

 

Hidden Nutrient Reservoir

It was made very clear to me, that the nutrient reservoir should not be in the dining area, but instead should be behind the wall in the pantry. That meant of course running the hoses through the wall. And, as you can imagine, this was the perfect time to use my 3D printer for a wall plate to make the holes in the drywall less drilled looking.

 

 

It does actually add a nice polished look to an otherwise industrial looking focal point of the room.

In the below picture  you can see the mess of wires and hoses that interact with the nutrient reservoir. I think putting all of this behind the wall was the right call in the end.

I have a basic submerged pump, an air pump to keep the water aerated, and a fish tank heater to keep the water at 78F, since it's winter and I'm hoping a little boost in temperature will help them grow more consistently. In this picture you'll see a couple of wifi plugs. These will get swapped out my a more complex system. At the time of writing this, I have no yet completed that, but we'll talk about the strategy in further sections.

 Worth noting, is that the system does not drain as fast as it pumps. I used the same size hose on the inlet and the outlet, which may be the contributing factor. So it is paramount that the pump does not run for more than a minute at a time, otherwise I will easily get overflowing. An attempt to remedy this was to add an air vent to the outlet. It seemed to help a little, but not nearly as much as I was hoping that it would.

Control System

Just like I can't avoid inserting 3D printing into every project, it's also hard to avoid adding some kind of digital/electronic/control systems as well. The WiFi switches weren't working very well for me any way, and I've wanted to build something like this for quite some time. 

The overall plan is to build a four switched outlets powered by a RaspberyPi Pico W. With four inputs for connecting temperature probes (or other sensors) if needed.

I started with the electrical work, routing power through a bank of relays. As well as a 5V power supply for powering the low voltage side.

And that's as far as I've gotten! As I progress I'll update this.

Bill of Materials

Nearly every thing I used was pretty easy to source. Here it is:

Main Structure

1. 8ft of 3" PVC
2. 4 x 3" end caps
3. 4 x 3/4" reducers
4. 4 x 3/4" x 1/2" push fit elbow
5. 4 x 1/2" NPT to hose barb
6. 20 ft of nylon tubing
7. Shelving brackets

Nutrient Handling

1. Water pump
2. Air pump and stone
3. Aquarium heater
4. Food safe bucket
5. Wifi switches (If not using the custom system) 

Control System 

TBD