Butterfly

While I was filming my latest video, this butterfly landed on my hand.  In the past, I’ve received several questions about why I don’t put screens on the greenhouse vents…this is why!

(Sorry it’s blurry, this is a screen grab from the video and the camera wasn’t focused for the close up shot!)

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Adding Automatic Vent Openers

I finally get to work on some of the more exciting things in the dome.  Automation!!!  I love being lazy!




A few years ago I made up some vent openers which use windshield wiper motors. They work well for the small greenhouse, but the frames have had some structural problems in strong winds.  For the dome greenhouse I’m using linear actuators to operate the vents.  The actuators have a lot more lifting strength and can withstand stronger wind forces.

To attach the actuator to the window frame, I took a piece of angle iron and made a cross brace.  The brace will fit about half-way up the vent.  I cut off a section from each end so that there were tabs that would be used for bolting the brace into the face of the vent frame.  I then welded a couple of tabs into the bracket which provided the connection linkage for the actuator.  After rounding over the edges and cleaning up some of the welds, the bracket was attached to the vent frame.

The rest of the braces are standard steel bar stock that are bent at slight angles.  There are four of them which go from the greenhouse struts to the back side of the actuator.  Because of the odd angles of the dome, a few of braces need to be bent as compound angles.  If this was a traditional vent the angles would have been much simpler bends.

I temporarily bolt the top brackets to the back side of the actuator and mark where the brackets connect into the dome’s strut.  It wasn’t necessary, but I set the actuator to be level when it was closed, simply for aesthetics.  I drilled out the first hole in the dome strut and attached the bracket.  Once the pieces start to hold themselves in place, it’s much easier to mark and attach the remaining brackets.

The bottom brackets are marked and installed the same way.  It’s just a bit more critical to make sure they are placed properly so that the vent is pulled completely closed when the actuator is fully retracted.  Once all four brackets are secured, the pyramid shape from the triangulation creates a sturdy mount for the actuator.

Now that it’s fully assembled, a quick test is in order.  All the pieces are cleaned and painted to give the system a nice new look!  Once the paint is dried, it’s a quick reassembly and then time to it get wired to the controller.

A regular two-conductor wire is used for each actuator and each vent opener has a line that runs back to the controller.  The actuators have built in limit switches which stop the motors automatically.  To open and close the vent, you just have to reverse the polarity of the power in the wire.

The thermostat controller is a prototype six-relay control unit that can be programmed to set each vent to open on independent temperatures.  The unit can be programmed to sample the temperature at predetermined intervals and also delay the change between relays so that all the vent motors aren’t running at the same time.  This keeps the unit from drawing too much power all at once.  Each relay can also be disabled and forced into an open or closed position.  There are more details about the thermostat in the description area of this video.

Thanks for watching.  Don’t forget to “thumbs up” this video if you want to see more like it in the future and feel free to leave comments too.

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Building the Aquaponic System Part 2 of 3

This is the second video in my series on how the aquaponic system is set up in the geodesic dome.  It details how all the plumbing is done.




In this second video, I’ll show how all the remaining plumbing is installed.  I’ll start with the line that runs from the central sump tank back to the main fish tank.

The pump is a standard quarter-watt sump pump with a float switch.  Eventually this will be replaced with a 12 volt DC bilge pump when the solar system is installed.  A threaded fitting is used to connect the pump to a 1 inch PVC pipe.  The piping is rated for potable water.  Then a check valve is in-line to prevent any water from back-flowing into the sump.  Next there is a union which allows the sump assembly to be easily removed in case it needs any maintenance.  Then the rest of the line that goes to the fish tank.

Since all these lines will be under some form of pressure and are being jolted from the pump turning on and off, they are all glued together with standard PVC solvent.  Also before using the system, all the piping is flushed out to remove any loose solvent or PVC shavings that may be remaining inside the pipe.

A little Teflon tape or liquid Teflon works great for threading various pieces together.

Earlier, I buried a section of 4” pipe to use as a conduit between the sump and the fish tank.  This is how the piping and electrical will run between them.  Having the union on the pipe really made it easy to lower the pump assembly into the sump and connect it to the rest of the line.  Don’t forget that this is a temporary pump until the solar is installed, so I just let the electrical run across the floor instead of through the conduit.

At the fish tank, the line comes up and out of the ground and over the tank’s edge.  I drilled a couple of holes near the lip of the tank so that the pipe could be secured to the edge.  Then I attached a 45 degree elbow to shoot the water down into the tank.  Setting up the pipe to drain at this angle forces the water to slowly swirl and most of the solids at the bottom of the tank will eventually work their way into the center.

Here are some of the details on how the fish tank overflows into the large buffer tank.  At the bottom center of the fish tank, there’s a 2 inch to 1 inch coupling that has a bunch of slots cut into it, acting as a screen.  This allows small debris through, but not the fish.  As the water level rises above the pipe, it starts a siphon which creates a strong suction at the bottom of the tank.  Any of the sediment that has worked its way to the bottom center gets sucked up and sent into the buffer tank.  The water entering into the buffer tank flows out at an angle which creates a swirl in the tank, slowly moving the sediment to the center where the pump for the grow beds is located. At the top of the pipe, there is a 1/4” hole drilled into an end-cap.  As the water level goes back down, the hole is exposed and the siphon draws in air, which breaks the water flow.  This is a very effective method for flushing out heavier solids over using a simple overflow.  A negligible drawback is that the water level fluctuates a couple of inches.

I start the overflow installation by drilling a hole in the tank and install a bulkhead fitting that has 1-1/8” threads.  I then install a threaded to slip-flit coupling so the 1”PVC pipe will attach to the bulkhead fitting.  The pipe then goes straight down into the buffer tank and then has a 45 degree elbow to shoot the water out at an angle.

Here is the pipe assembly for inside the fish tank.  The screen is a 2” to 1” coupling that I ran over the table saw to make some slots into it.  This piece sits directly on the bottom of the tank.  The pipe comes up to a tee where one end goes to the cap with the hole drilled into it, and the other end drains out to the buffer tank.

The piece that goes to the bottom of the tank wasn’t glued into place so that I could remove it just in case something does clog it.  Also the piece with the cap isn’t glued so that I can adjust the height of where it can stop siphoning.

Once the system was established, I discovered that pellets of food and duckweed would plug the siphon-break hole.  A piece of screen over the area quickly solved that problem.

This is a view inside the buffer tank showing how the water pours into it to help create a swirl flow.  The bilge pump sits at the bottom of the cone shape sucking up any solids that eventually work their way to the bottom of the cone.

The supply lines from the buffer tank to the grow beds are 1” PVC lines rated for potable water.  To keep them out of the way, most of them are buried under the floor.  Originally, I wasn’t exactly sure where all the beds were going to be placed and didn’t want to bury these lines while building the dome.  Instead, there’s a layer of sand under the brick.  The bricks and sand are easily removed and the supply line drops right into place.  Once all the plumbing is laid down, the sand is replaced and compacted and the brick flooring is reset.

At each grow bed, the supply line comes up from the floor and goes to a ball valve, which is used to regulate or turn off the flow of water. It then goes over the edge of the grow bed and pours the water directly in to the expanded shale.

The pump for the grow beds is a 12 volt DC bilge pump rated for 1100 gallons per hour and is located in the bottom-center of the buffer tank.  It is connected to a union so that is can be quickly removed for maintenance. 

Along the supply line there is a branch that feeds back into the tank where there are a few small valves which are tapped into the line.  These are used to shoot water back into the fish tank to help aerate the water and keep it moving a bit.  The fish also enjoy playing in the stronger currents.  I’ve also place a net over the tank to help prevent the fish from jumping out….again.

Up next in the series will be the grow bed design and construction.  For additional information, please see the description box or leave a comment.  Thanks for watching!

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