Urban Survivalists

Hey everyone!  We have updates for you on the aeroponics system. First of all, we are going to show you the results of a test sprout of different kinds of seeds with the fogger. Then, we are going to show you how to make a fog chamber prototype. As with all things on this blog, we reserve the right to upgrade later. We just wanted to conceptualize how the fog  chamber might work.

Test Sprout Results

We decided to see if the seeds would sprout given water from the fog unit only. In order to test this idea, we used an iced tea jar with plain water and the fogger inside. Over the top, we stretched trench cloth and placed the seeds on top of that. We moistened the trench cloth initially to make sure that the capillary action of the water would work through the trench cloth. We decided to test the fogger with just water and no nutrient solution to see if the plants would sprout. You can see a picture of the tea jar and fogger configuration we used to fog the seeds in the sketch below. We had to put two bands of duct tape over the tea jar lid to keep the water from splashing onto the trench cloth. We only wanted the fog to come in contact with the seeds and not macro-scale droplets. Even with our bands of duct tape, the water still ended up splashing on the trench cloth so we still don’t know if the fog alone will sprout the seeds through the trench cloth.

The results of this experiment were impressive. In under three days, 2 days and maybe six hours of so, the pea seeds had sprouted substantial inch-long roots! Once the roots had grown out to this length, we poked holes in the trench cloth and guided the roots down through into the fog directly. During this whole time the fogger was kept on full time. So, at the very least, we know seeds will sprout readily when placed on a moist cloth with no nutrients. This is good news for our Aeroponics system!

This is an image of our tea jar test set-up.

Here is an image of the sprouts after three days of fog exposure in the tea jar set-up.

Fog Chamber Prototype

Next we wanted a more substantial and permanent fogging apparatus that we could hook directly up to our growing frame. We decided to use the ubiquitous five gallon bucket. Below we have our standard construction sequence. Below is a sketch to give you an idea of what we were going for when we decided to make the fog chamber. You will notice a raft looking structure to place the fogger units on. We decided to do this in order to keep the foggers at the optimum level to produce fog even though the water level in the bucket might be decreasing. The raft will move up and down in elevation with the water level in the bucket, at least in theory.

Materials:

• Five Gallon Bucket
• CPU fan for a computer, and a power supply to run it
• Two fogger units
• 2″ x 5″ x 1/4″ plastic sheet (from a cutting board works well)
• Two small glass jars
• Zip ties of varying sizes
• Box cutter

Steps:

1. Cut a hole in the side of the bucket large enough for the CPU fan to fit in.
2. Put the CPU fan in the hole, make sure the hole is small enough that the fan sits snuggly and will not fall out.
3. Put two large zip ties around each of the glass jars, one on either end. We will be using these as attachment points for the zip ties holding the platform.
4. Drill four holes in your plasic sheet, one at each end of the short sides that will accommodate the body of your smallest zip ties but not the latch part of the zip ties.
5. Connect the zip ties around your jars to the holes in our plastic board as per the pictures. Your objective is to create two loose hanging floats for the board. Keep the zip ties loose so that you can adjust the depth of the platform under the water if need be.
6. Connect the fogger units to the “top” side of your plastic board with some zip ties. Make sure you do not put the ties over the small, round transducers as this will reduce or eliminate your fog production.
7. Use duct tape and tape a square of clear plastic over your fan unit on the inside of the bucket to prevent splashing form getting on the fan during operation.
8. Done!

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Comments

The small flap of plastic serves two purposes in this design: 1) it keeps the water from splashing onto the fan or out of the bucket, 2) it minimizes the loss of water by evaporation and by flowing out the hole once the foggers start. Some weights at the bottom edge of the plastic might also be in order depending on the weight of your plastic.

Now that you have the unit set up, you’ll want to test it. Turn on the foggers, wait a few seconds for them to build up a head of fog, then turn on the fan and watch the fog bank billow out! Good times!

Of other note, the green PC fan that we bought proved to move very little air in comparison to what we needed. So we hooked the new fan to pam’s giant computer for more cooling, and decided to use an older fan we had on hand because it moved more air.

Next Time

Next week, we’ll dive into the electronics to build this system. We plan on running this all from a microcontroler like our filter box but with the possibility of some cool new features. We recently picked up a Tower System from Freescale. This is a cool kit focused around the MCF51CN ColdFire MCU. Get more info here and here. They look to be pretty sweet systems that should allow us to make our aeroponics system visible on the web with very little hassle. We want to have the temperature, the humidity, whether the foggers are currently on, and a web cam of the setup available in real-time over the web on right here!

To get there, we are going to develop the electronics in two distinct phases. Phase one will be our standard proto-board and Arduino setup. Phase two will be those same protoboards as nice manufactured PCBs and the Arduino replaced by the Tower System and a little bit of online goodness! Those are ambitious plans so give us a bit to make it all happen. Pam is going to be doing all the development work on the Tower and the code will all be posted here and at TowerGeeks.org

Here are the new tower electronics that we hope to eventually run the aeroponics system from.

Until next time, be safe and sustainable!
P&S