Monday, July 30, 2012

Building the Aquaponic System - Part 3 of 3

This is the last of the series on how my aquaponics system is put together.  It details how the media and raft-based beds are designed and assembled.

This video shows how the various grow beds are set up in the dome greenhouse.  In order to maximize as much floor space as possible, all the beds are custom fabricated.

There are three media-based beds located in the center that are filled with expanded shale.  The beds use bell siphons to flood-and-drain the water which drains directly back into the central sump tank.

Along the perimeter wall, there are 2 media beds.  These beds are set higher than their neighboring raft-based beds and drain directly into them.  This method works very well since the media beds filter all the solids from the system and minimizes the amount of sediments that could accumulate in these raft beds.

I’m undecided on the last two beds and may make them rafts beds and interconnect them with water bridges, or have one (or both) be media-based beds.  It all depends on the types of crops I eventually decide to grow.

I drew a chalk outline on the floor that acted as a template for all the beds.  The frames are made from 1/2 inch black pipe that I welded together.  I’m using steel since it is very strong and doesn’t warp like wood, and is resistant to bugs and rotting.

The sides of the beds are 12 inches high, which seem to be a good depth for both raft and media growing.  Leaving for a little extra space along to top so the water and media doesn’t spill out, the growing depth is around 11 inches.

The bottoms have support braces spaced every 12 inches.  My original plan was to have the raft beds sit directly on the brick floor, but I had one critical design flaw in the dome… I ran the ducts for the geothermal out through the floor and the beds would block them.  I had to prop all the beds up on a brick so the air could pass under them.

When the steel cools off after welding, a little black rustproofing paint is applied which cleans up the look a bit.

This is one of the raft beds that was going to placed directly on the floor but interfered with the heating system.  Instead, a few bricks are placed under it as feet and the frame is set into place.

Back in the spring, my neighbor and I milled a bunch of the white pines that I had cut down from the greenhouse site.  Some of them are cut to 1 inch thick and are being used to line the grow bed frames.  I just laid them into place and let them overhang over the edge, marked a cutting line, and cut off the excess.  They lie down nicely and make a very strong decking for holding the liner.

The media bed is assembled the same way but is set on stacks of extra bricks.  The bottom elevation is higher than the top of the raft bed so that it can drain into it.

I purchased a large roll of EDPM pond liner.  It’s very heavy and difficult to work with, but is hard to puncture and is UV resistant.

The liner covers the entire bed and I carefully make sure it is properly centered so all the edges can be draped over the lip of the bed.  I did discover that it’s a lot easier to work with the EDPM if it warms up in the sun…even though it’s hot on the hands.  I just keep working it into each corner making sure that there is plenty of material to fit into the corners.  If there is a gap between the wood and the liner, it could stretch and eventually tear under the weight of the media and water.  I found it was very helpful to set bricks on the liner once I had it in position to hold it in place.

The corners can be a bit tricky.  Once I got the liner in place, I cut off some of the excess to make it easier to manipulate.  Then I could fold a nice and clean corner. It’s important to remember to make sure the edge of the liner is always going to be over the lip so water won’t leak out!

On the outer edge of the bed, I added a strip to anchor the liner into place.  The screws go through the strip and liner, and secure into the side boards.  The extra liner is cut off which makes for a clean looking transition from the liner to the bed.

The media beds have bell siphons in them.  I’m using a bulkhead fitting through the bottom of the bed for the drain.  So that the liner doesn’t get tangled up in the hole saw, I sandwich the liner under a piece of scrap board.  These boards a still somewhat damp and the saw is old and worn out so I have to keep cleaning the sawdust from the bit, but eventually I make my way through.

After cleaning the debis out of the area, the bulkhead fitting fits perfectly through the hole. It has a rubber washer that seals against the EDPM liner and fitting.  Under the bed, it has a large nut that tightens the fitting in to place.

The stand pipe and drain lines are made from 3/4 inch thin-wall pipe.  These bulkhead fittings have a 1-1/8” threaded fitting since it’s what I had in my assorted collection so they need a threaded to slip-fit coupling to reduce it to the right size.  I use a temporary stand pipe and fill the grow bed to test it for leaks.  I like to fill the beds right up to the rim to test for a worse-case scenario.  Plus it’s a great way to check to see if the bed is level and add any shims to the legs for minor adjustments.

Once everything looks good I put in the bell siphon and media guard, and the bed is ready for the expanded shale.  Since I recorded this video, I’ve changed the bell siphon design a bit, so click on the link to see these details.

This type of bell siphon uses a trap which helps it to start.  The trap assembly is screwed into the bottom of the bulkhead fitting and a section of pipe is attached to the trap and extends to drain into the raft bed.

The liner for the raft bed is installed the same way as the media bed.  It was actually was a bit easier setting it up in a larger area.  Once the liner was installed, I flooded the bed and removed the temporary holding bricks.

I’m using expanded shale for the growing media.  I just give it a quick bath to rinse off the dust, screen out some of the smaller stones, and fill in each bed, one bucket at a time.  I like using the shale since it’s about half the weight of stone and easy on the hands while digging in it.  Most of the corners are rounded over which will minimize the risk of it puncturing the liner.

Since the raft beds aren’t square, I needed to come up with an efficient design to maximize the space of the bed.  Using square rafts would never fit properly.  I design a single row raft that was tapered so they would “fan out” in a curved pattern when they were placed in the bed.  As the taper became wider, I placed the holes closer together.  For a mature plant, the amount of space per plant will be the same, it just is not a perfectly round or square area.

The seedlings will start from one side.  Every few weeks, a new batch will be added and the older seedlings will get moved over.  At first, the width of each raft is narrower than the space that the plant will need, but as it grows, I add a spacer in between the mature plants to give them a little more room.  By doing this, I can compact the new plants together without having to transplant them from a compacted raft into a normal-spaced raft.  Each bed will hold about 208 lettuce in about 44 square feet.

The remaining area can be used for seedling starting.  Currently the space works well for growing duckweed.

The rafts are made from 1” Dow blue board foam.  I made up a template so each raft was cut identical.  The template also has holes that marked the location for each hole for the net cup.  I used a 1-7/8 hole saw which makes for a snug fit for the 2” cups.  I found it was fastest to drill the hole half-way through, then finish drilling from the other side.  This left a bit of the plug sticking out so it was easier to remove from the hole saw.

I fill the net pots with a little bit of damp shale and drop in one or two seeds.  The dampness makes the seeds stick to the shale so they don’t just drop through.  The rafts push right over so the new set can be placed at the beginning of the bed.  Once the plants mature and need more space, the filler rafts can be inserted between each row.  So far, the lettuce has a good healthy root system and will be ready to harvest in a couple of weeks.

Thanks for watching this series, don’t forget to like this video and join us on our Facebook page.

Friday, July 20, 2012

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!

Saturday, July 14, 2012

Building The Aquaponic System - Part 1 of 3

Here is the first of three videos on how the aquaponic system is assembled in the geodesic dome.  This first video recaps some of the installation that was done during the dome construction and shows a general overview of how the entire system operates.

Hi, I’m Rob Torcellini

This video series will show you the various details about how I set up the aquaponic system in the geodesic dome greenhouse.

This first video, I’ll explain how some of the components were installed during the dome construction.  I grouped the video sequences by the component, not in the chronological order of when they were installed.

First is the central sump tank.  This tank is used to catch all the water that is draining from the grow beds and a pump returns the water to the main fish tank.

While the foundation hole was empty, I built a brick wall around the tank.  The wall leaves a gap around the tank so that it can expand and contract when the temperature changes. If this wasn’t installed, eventually backfilled dirt would crush the plastic tank.  The end of each pipe draining into the sump has an elbow to help swirl the water inside the tank, which will help to reduce sediment buildup.

Also while the foundation hole was empty, I installed a large sump tank which is used as a buffer to compensate the changing water levels in the grow beds.  The water from the fish tank drains into this tank and then pumps the water into the grow beds.  This tank holds about 500 gallons of water and has a cone bottom, allowing sediment to work its way down and sucked out by the pump.

This tank also has a block well-housing built around it to protect it from getting crushed.  This is a view of the central sump and buffer sump wells while they were being backfilled.

There is a network of drain pipes that are buried under the floor.  These are used to collect the water from the assortment of grow beds that are throughout the dome.

The drains are 2” lines and are set at a slope to drain the water into the central sump.  There are extra drain inlets that come up to the floor which will not be used, but at the time I installed this, I had not decided on the final layout of the grow beds.

All the pipes are backfilled with sand to protect them from damage. This allows me to easily dig them up if any maintenance needs to be performed.  After I lay down the final floor, the drain pipes are cut flush with the floor.  If any dirt or insects fall into the pipes, they will just get flushed into the sump tank.  Here is the final view of the drain pipes with the central sump tank.

The last component is the main stock tank.  This is placed in the northern section of the dome to help minimize light and algae growth.  The tank is a scrap tank that I salvaged and it had a bunch of fittings that needed to be capped.  After leveling out the area with a sand base, the tank slid right into position.  While I was installing the drainage pipe, I buried a scrap section of 4” pipe between the sump and fish tanks.  This allowed me to run the pump and electrical lines between the two tanks under the floor. Since the tank was so tall, I wanted people to be able to easily see the fish so I installed 2 windows.

This is a functional overview of the entire system.  Water from the fish tank overflows into the buffer sump tank.  It is constantly pumped, along with any solids under the floor and into the grow beds.  The line to each grow bed has a valve to help regulate the flow.  There is also a line that feeds back and shoots water back into the fish tank to help aerate the water.

Using bell siphons, the grow beds continuously flood and drain.  The inner beds drain directly into the sump tank, while the outer beds drain into a raft system (not shown), which then drain into the sump.

There is a float switch in the sump tank that pumps the water out of the sump and back into the main fish tank.

The large sump tank is use to maintain a consistent water level in the fish tank.  Since the levels in the grow beds and central sump tank are constantly changing, that difference in volume has to be offset elsewhere.  Not only does this help with the water levels, it adds additional thermal mass to help keep the water temperature from fluctuating each day.

In the next video I’ll detail the plumbing installation.  Thanks for watching!

Thursday, July 12, 2012


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!)

Friday, July 6, 2012

Automatic Fish Feeder

Time to add to my laziness and add some more automation.  I no longer have to feed the fish a few times a day...however I still like to just stand there an watch them.  What is it about them that's so mesmerizing???

This is a small automatic feeder that I made which holds about 4 tenths of a liter of fish food and has been running for a few years.  I built this larger one for the new greenhouse which holds 2.8 liters.

The feed is controlled by a regular 3/4 inch wood auger bit which fits nicely into a housing which is a piece of 3/4 inch black pipe.  This is driven by a 12 volt DC gear motor I got from a surplus store.  This is a great motor since it has a slot instead of a drive axle so it’s easy to make the auger bit fit into it.

First I cut down the auger bit to the right length and grind down the shaft so that it fits into the slot of the gear motor.  I then cut out the center of the black pipe.  This is where the feed hopper will connect to the auger housing.  A small piece of flat bar is used as a mounting bracket which will allow it to be mounted to the tank and attach the motor to the shaft.

After carefully setting up the pieces, I tack weld the auger housing to the mounting bracket, then remove the motor and finish welding the pieces together.

The feed hopper is made from an old computer cover.  I made up a cutting template for the various pieces and sprayed adhesive to the cover to hold the templates while cutting.

I built in some tabs to the hopper walls so I could weld the pieces together.  This is the point in time where I which I owned a metal break, but had to improvise with my vice and hammer.  Luckily, the bends were not too complex.

After all the pieces were bent into shape, I ground off the paint so the seams could be welded together.  I also drilled holes through the walls where the tabs would connect.  This is so I could weld a tack through the hole to connect the thin sheets together.  It’s similar to riveting the pieces together.  

When the hopper is welded together, I grind the welding tacks down so they are flush with the sheet metal.  The last bit of welding is to attach the auger assembly to the hopper.

I am fortunate to have access to a nice sand-blasting cabinet.  This quickly and easily removes any loose paint and rust and makes a really clean surface to paint.  After a couple of coats of paint, it looks almost as nice as work done by a pro ….almost.

I made up a level switch that turns on an LED to let me know when the feed is getting low in the hopper.  I took a bamboo skewer and hot-glued it to a micro switch.  The newly extended lever reaches into the hopper and has a float that hangs from it.  When the level goes to low, the float will pull down on the lever and light the LED.  I also added a momentary switch into the box which allows me to turn on the auger in case I feel like giving the fish a bonus snack.

I mounted the level switch box to the hopper and connected the motor wires through the box.  Then the new feeder was bolted to the side of the stock tank.  For now, I connected the feeder to one of our IX-180 index timers.  It is programmed to run the auger bit for 20 seconds, four times per day.  The extra input of the timer is used to monitor the water temperature in the tank.  Eventually, the feeder, vents and other controls will be connected to a master automation system.

Here’s the float that sits on top of the food, when it gets low enough, it just pulls down on the lever and turns on the LED and this is the feeder in operation.     Thanks for watching!  Make sure you subscribe to this channel for more great videos!