Final Greenhouse Design

Construction starts today, so I thought Id share the final design Im going with.

Because I am constrained to have the structure less than 52" above my patio, Ill be digging a sunken aisle down the middle of the greenhouse, between the growbeds. I had wanted to have a 300 gallon fish tank, but Im willing to settle for a 150 gallon (600 liter) stock tank for the fish with a 100 gallon (400 liter) stock tank for the sump. The smaller tank will allow me to have an aisle through the entire greenhouse, which should be simpler than having the center blocked by the tank. The plan is to raise blue gills and redears, with a catfish or two.

The little green circles are planned vertical towers I will be making out of 4" PVC sewer/drain pipe - you can buy these at Aquaponicsource. Im going to try my hand at making them myself, since I think Ill break even making 6 of them.

The large green oblongs are the 50 gallon rubbermaid stock tanks. The two overlapping the fish tank will just drain into the fish tank. The fish tank will have a drain near the top that will be plumbed to drain into the sump. The vertical towers and the two grow beds overlapping the sump will all drain directly into the sump. So this will be a hybrid CHOP/CHOP-2 design.

Today Ill probably wont get more than the foundation in, but the die is cast...

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Great deal on a Greenhouse

The Harbor Freight 10 ft. x 12 ft. greenhouse is nicely affordable. You cant get a store-bought greenhouse of this size for anything close to the $850 Harbor Freight price.

Because its spring, Harbor Freight has reduced the price on their 10x12 greenhouse by $50. At my local store, the sale is good through the end of May.

Better yet, you can get an additional 20% off through May 15th (google Harbor Freight coupon).

So if you have the 20% coupon and go to the store, you can pick up a 10x12 greenhouse for only $640 (plus tax). If you have to have it shipped, tack on $100 S&H.

This greenhouse gets decent reviews. Typical problems can be overcome cheaply. YouTube has numerous videos on "Harbor Freight greenhouse improvements." John at Growing Your Greens gives a nice overview of possible improvements (fast forward to 4:40). An additional idea is sealing the edges of the panels with waterproof aluminum tape.

If you, like me, dont need a greenhouse at the moment, check out the sale price on the 45 watt solar panel kit. Its not as cool as a Solman 135 watt generator, but its easier on the budget...

15 May update - Found another possible greenhouse option at Home Depot. Id have to modify my layout to fit the 10 ft. x 10 ft. footprint, but Im sure I could get it to work. $249 delivered straight to my door is rather attractive (though my community covenants would still prohibit me using this particular product since its 8 ft. tall ::pout::).

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More Greenhouse Fun

Small Green House Plan from North Carolina Cooperative Extension

Ive learned a lot from stuff posted online about how to create hoop houses. Probably the most useful document to date is "A Small Backyard Greenhouse for the Home Gardener" from the North Carolina Cooperative Extension. The instructions give you a 14-foot long greenhouse that is 12 feet wide and 6 feet high.

But I dont have space for a full-up hoop house. Ive been messing around with powerpoint, trying to figure out how to fit a 300 gallon tank and six 50-gallon grow beds into an 8-foot wide space in the minimum length. I think Ive got it:

Ill talk about the aquaponics layout later. For now it is sufficient to say that I should be able to fit everything in a 8 foot wide by 14 foot long footprint.

Instead of PVC pipe, Ill be constructing the body of my greenhouse out of 1/2" Electric Metallic Tube (EMT) conduit. Conduit is pretty inexpensive, running just over $2 for a 10 length. Its stronger than PVC, and I can bend it to the shape shown above.

In fact, Ive figured out the "recipe." Conduit benders can be had for ~$30, and are marked for bends of standard size (10, 22.5, 30, 45, and 60 degrees). If youve not used a conduit bender before, know that the "center" of even a shallow bend will be 1-2 inches offset from the start of the bend. Many benders will have a mark that shows the location of "the exact center of a 45 degree bend." No matter what angle you bend, the center will be pretty close to that 45 degree center mark, so position your tubing accordingly.

1. Mark the pipe in the middle (5) and make marks 8", 21", and 34" from either end.
   
2. Bend the pipe 22.5 degrees at the 5 mark. [From this point on it is useful to get a partner who can hold the pipe so the rest of the bends are in the same plane.]
   
3. Move the conduit bender to the 8" mark and make a 60 degree bend.
   
4. Move the conduit bender to the 21" mark and make a 10 degree bend.
   
5. Move the conduit bender to the 34" mark and make another 10 degree bend.
   
6. Flip the pipe and bend the other side (60 degrees at 8", 10 degrees at both 21" and 34")
   

When youre done, your ten foot pipe should look like this, and the distance between the two leg-stubs should be 8 feet. Or at least, when I did this, this is what my pipe ended up looking like:

This shape minimizes height delta between the edge and center of the structure, provides strength along the roof "faces," and gives a peak at the center to help shed snow. For a 14-foot long greenhouse with frames every 2 feet, youll be making 8 of these "tops." If they dont lay flat, you can do some "correction" with the conduit bender.

Next, create 16 EMT "legs" by cutting 10-foot lengths in half with a pipe cutter or hack saw. These legs will be connected to the tops using EMT set-screw couplings. Position the set screws so they face the inside of the frame, so they wont snag the plastic sheeting youll be draping over your structure.

From this point you can pretty much follow the instructions for the North Carolina hoop house from the top of this post. But instead of a wide, short semi-circle, your greenhouse will be only 8 feet wide and about 7 feet high. Also, you will be installing a simple door in each of the two end walls, so you can access the beds on either side of the fish tank.

Two last points - I plan to screw three 14-foot lengths of EMT to the frames with EMT 2-hole straps and zinc sheet metal screws. These will serve as a ridge pole and lateral stiffeners. Also, since part of the location where Im putting this is brick patio, I plan to connect the greenhouse to a support under the fish tank. I figure 300 gallons of water (2,400 pounds!) is enough to keep the house from "shifting."

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Greenhouse Layouts

The Royal Victorian 10 x 15 Greenhouse

I have a relative who happened into a fair chunk of cash and bought a million-dollar home. Before the market fell, it was a multi-million dollar house. But the market has fallen, plus this house doesnt face the street. The other day it occurred to me that a lovely greenhouse could improve the curb appeal of this house.

I mentioned the idea of a greenhouse to my relative, and they were interested in considering something like the Royal Victorian. They even have waste heat that comes out that side of their house, that they could divert into the greenhouse during the winter.

So I got thinking about how I would lay out an aquaponics greenhouse, if I had a 10-ft by 15-ft floor to work with...

Possible Layout for 10-ft. by 15-ft. Greenhouse

Even though my relative can direct heat from their house into the greenhouse, I took the liberty of putting a Rocket Mass Heater into the layout. The beauty of the Rocket Mass Heater is it can augment the greenhouse temperature if the waste heat from the main house isnt adequate.

Im not sure how much exhaust piping a Rocket Mass Heater can drive, or if my two-exhaust concept is viable. But it would be nicely symmetric...

But what about adding a BioSand Filter to produce drinking water from a rain barrel or stream?

10-ft by 15-ft layout with BioSand Filter

The beauty of having a BioSand Filter in a heated greenhouse is it wouldnt freeze up in the winter. Your fish and pets could have clean water no matter what ice storm or flooding or water main break might happen.

But what about those of us who cant afford a Royal Victorian greenhouse?

First I modified the layout to fit a 15-ft by 8.5-ft greenhouse footprint. You could make one of these out of EMT conduit, like the one I have in my backyard. This aisle is wide enough to allow wheelchair access (36-in).

8.5-ft by 15-ft layout with BioSand Filter

The vents from the Rocket Mass Heater would be pretty close to the fish tank and sump, but the Rubbermaid tanks can withstand 190 degrees Fahrenheit. This assumes my idea of splitting the outflow isnt fundamentally flawed...

Next we look at what could be done in an 8.5-ft by 12-ft footprint, close to what I have in my back yard:

8.5-ft by 12-ft layout

In the 8.5-ft by 12-ft footprint, I dont have room for the BioSand Filter. The rocket mass heater is at the end (which is a mere 3-in from the wall - presumably constructed from non-flammable material in the vicinity of the heater). Ive moved the growbeds so they overhang the sump and fish tank by a few more inches. This will make it a little more difficult to access the fish and pump, but the beds will be stable on the cinder block supports, and there is still adequate space to reach the fish and pump.

In the last layout, I thought about how I might accommodate a Rocket Mass Heater and a BioSand Filter in the large Harbor Freight greenhouse (10-ft by 12-ft):

Layout for 10-ft. by 12-ft. Greenhouse

This shows a more traditional (i.e., proven) run for the exhaust from the Rocket Stove.

So... I have a plan to propose should my relative decide to go forward with the fancy Royal Victorian greenhouse. I also have a plan for how I could at least accommodate a Rocket Mass Heater and wheelchair accessibility in something close to the footprint Ive currently got in my back yard, if I decided to make the necessary modifications.

Sweet!

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Poor Mans Greenhouse aka High Tunnel

$50 Greenhouse at doorgarden.com

One of my early rants focused on the fact that it gets cold up here in the continental US. And not everyone has a greenhouse.

But with the White House using hoop houses and the USDA running around helping folks construct high tunnels, Ive been seeing a lot about how one might be able to do a greenhouse for far less than $$$. The idea is you bend PVC pipe between anchors at either edge of the area, then drape the hoops with 6 mil polyethylene. Done.

Some things to consider.

Structural Stability


Door Garden reports the structure sprang back to shape once the snow was removed. But there are various ideas for making the initial structure stronger.

1. Go Gothic - theres a reason those northern barbarians didnt use the classic roman arch - because it was liable to fail under load (think snow). A pointy arch can do beautiful things. Check out the post Another snow day at tinyfarmblog.com.
   
   
2. Use metal conduit rather than PVC. Turns out a conduit bender can be had for less than $40, and metal conduit is about the same price as PVC. Check out the Chiots Run post about Building Hoop Houses out of Electrical Conduit.

Size constraints

• Tiny yard. I live in a townhome. The entire thing is only 20 wide and about as deep.
  
  
• Covenants. Im not allowed to build anything that is taller than the fence around my yard.

Im thinking of using the metal conduit to achieve a slightly more complex shape that would give me enough space for two rows of aquaponic growbeds without being taller than 6 feet. Here are some initial sketches:




The tall, flat wall will be next to the northern side of my fenced area. For the 8 x 15 plan shown, the conduit, bender, and 6 mil sheeting will run me about $250 (prices at Home Depot as of 2/21/11). Add a door, some lumber, and chicken wire, and were around $300. Id do a CHOP2 configuration, so there will be ~200-250 gallons of water in the system even though the tank, itself, is only 150 gallons. The Rubbermaid growbeds are $130 for the 150 gallon tank and $70 for each 50 gallon growbed and sump tank, so those would run me $700. Total $1000.

But Id have no cost for grow-lights and the electricity needed to run them. Thatd be sweet.

Too bad I cant use tilapia outdoors. Ill have to figure out what fish could do OK outside. Goldfish always work - theyre cheap and dirty, perfect for aquaponics. But ornamental goldfish can be carcinogenic if theyve ever been treated with Malachite Green, so we couldnt eat them. Ill give my buddy at the Virginia Department of Game and Inland Fisheries a holler and find out what he recommends.

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