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Wanjun Gao

My first High Pressure Aeroponics growing experience! Part 1

Two weeks ago, I assembled a high pressure aeroponics system and started my first soil-less growing experience. It turned out that HPA growing process was fast. I made some adjustments to the nutrient spray volume through trial and error. Luckily the plant was resilient.

These are the photos from day 1, day 6 and day 8. Looks like I’ll be able to eat some tomatoes soon.

Day 1, 6, and 8 photos

Equipment and tools

I assembled the equipment with parts and tools from all over the world. I used Ebay, Amazon, and Taobao. My custom electrinical board was made by a company in Texas, and cases were put together by a processing mill in China that’s owned by my friend.

A little bit background about me:

Software architect in enterprise solutions, mobile apps, cloud computing, websites, and data integration. And recently, I am doing PCB design, firmware programming for IoT in my spare time.

Back to the equipment, here is the photo right after I put together:

Key components:

  • Pump: RO water pump with 1MPa (145 psi) working pressure. And it is quiet, less than 45db when it is running.
  • Tank: 1-liter tank. I don’t like big tanks for the following reasons: 
    a) I only need a small amount of nutrient,
    b) I don’t like the nutrient going stale in the tank if they stay in for too long, and 
    c) If I need to change the nutrient, I don’t have to waste out the big unused portion in the tank.
  • Controller: Raspberry-pi + custom board with Atmega2560 processor serve as command center for sensors, pump controls, etc. I designed the board and outsourced the production to a PCB company in Texas.
  • Atomizers: Non-dripping ceramic sprayers. There are some fancy models with built-in filters too. However, I want to be cheap and it seems fine so far.
  • Solenoids: One solenoid for each atomizer. That way, I can control the spray schedule independently and reduce the impact of the pressure drop when the sprayer is on.
  • Growing Basket: AeroGarden spacer. I used cotton from cosmetic cotton balls as resting media, and it seems to be working great.
  • Power Supply: IP67 rated (water and dust isolation rating) 110VAC to 24VDC power supply. Safty first. After all, we are dealing with electricity and water at the same time.
  • LED light: I have not put it on yet. It is a 3 channel adjustable LED light. I will use it in later stage. Right now, I just tried to get the seed grow near a window.

Day 1: Assemble the system

Here is photo of the tools, materials, and spare system case.

parts and tools

After I put things together, it looked like this:

assembled equipment

One of the problems is the root chamber being semi-translucent. I suspect that things like algae and bacteria, might start growing in there too. I would need to tin-foil it soon.

The material of the chamber cover is fine, made from alum-plastic board, with holes fitted for AeroGarden’s spacer. I should have removed the protection film so that the photos would look cleaner.

Anyway, I hooked up the filter, pump, tank, atomizer, and ran a test spray.

It seemed working ok.

Then I duck-taped the pump’s inlet pipe to make sure it was always submerged in the nutrient liquid.

Then, I made a CGM (cotton growing media). I used the AeroGarden spacer, peeled out the cover, and inserted cotton fiber that I pulled out of the cotton balls.

CGM in the the system and being tested it out

I was able to see the misted water being captured by the cotton fiber.

(Note: The spraying volume was too much for the seed, which I discovered in the later days)

Then I set a tomato seed on the cotton, and over by a very thin layer of cotton fiber. (I am not sure if the covering layer makes a difference).

And then said a lot of prayers.

(To be continued: My first High Pressure Aeroponics growing experience! Part 2)