So I probably could have separated this into two different instructables, but I figured "What the heck, y'all will enjoy it all at once", right?
So this may not have all the tiny details but if you comment, I will do my best to answer any questions.
I have been wanting a greenhouse for a few years now but living in South Mississippi, USA, we are prone to hurricanes and even our summer thunderstorms pack a pretty hefty punch with 60-70 mile per hour straightline winds, so a PVC hoophouse with 6 mil plastic was not gonna cut it for me....so I decided to add on to my garden shed.
Step 1: Planning and Getting Started
I am the type of person who has to plan every detail before I get started so it is no surprise that this project took a while to plan and only a couple of weekends to build.
It all started with the graph-paper plan (view image for particulars). I changed the layout a bit during construction which is highly unlike me, but it was for the better.
The design is a 12' x 12' (est 3½ meter x 3½ meter)
My garden shed had two 6' sets of doors and one was really unnecessary so I used it to attach the greenhouse, give me access to greenhouse form shed, and allow all those carpenter bees that are boring in the rafters to have easy access to the plants in the greenhouse. Sure, they may make my roof cave in one day but my cucumbers and tomatoes will be pollinated well in the meantime.
Using some graph paper, I drew out my outline. I used 4x4 treated posts for the main verticals, dug 2' in the ground, concreted, and with right at 4' on the insides of beams (not on centers). I did it this way because of the width of my windows. My windows were picked up at a local salvage yard for $35 each and 4'x6'. I wanted the 4' part to be my width and the 6' part to be my height so the uprights are 4' in between each.
Note: MAKE SURE to get your base square. You are perfectly square when the measurements of your diagonals are the same and your widths are all the same. Take the time to do this and it will prevent headaches later.
Next I planned the roof layout. My roof was not going to be as heavy since I was using 12' polycarb corrugated panels. I only needed a center board that would support the entire weight (I went with 2x8x12) and then used 2x4x12's to run on 2' centers (the recommended width for the roofing panels).
Look at comments on pictures for some additional insights on initial startup.
Step 2: Finishing Up the Greenhouse
Since I had to create a slope for water drainage, I took the easy way out and simply followed the already sloping ground. Had I not done this, I would have needed to pull out a line-level and drop the bottom end some. Since I am not a carpenter, I had some odd angles and just played with it to make things work.
I AM VERY GLAD I TOOK THE TIME TO MAKE SURE THINGS WERE PERFECTLY SQUARE ON THE BASE AS IT MADE THINGS MUCH MUCH EASIER
I could have used T111 board or other outside plywood type board for the bits above and below windows, but decided to just use deck boards (also known as 5/4 (5-quarter) board) because I found it easier to work with and I had plenty left over from when we built our deck a couple years ago.
See image comments for more info.
Step 3: Getting Ready for the Aquaponics System
I have built numerous aquaponics systems and enjoy helping others plans theirs so I knew what I wanted to do initially and I also wanted to make sure I had room for expansion later so I maximized the space by cutting up 3 275 gallon (about 1000L) IBC containers. In order to get maximum space, I was going to have to dig...
IBC's are roughly 48" by 40" and 48" tall.
I wanted to bury the fish tanks so that only about 12"-18" were above ground. This would give my grow beds the ability to sit on top of them and be at an ideal height for working with and planting/harvesting. I also had to take into account that my smaller fish tank (I cut the top off one tank for a grow bed so it left a smaller (roughly 175 gallon (650L) fish tank) would need to be slightly higher to give me an easy gravity-fed drain (I actually used 3 1" pipes for drainage to provide plenty of aeration to larger tank) so the smaller tank sits about 2" higher for this reason.
Digging is a lot of work and I am no spring chicken so I used a post hole auger to help get them started and when I got tired of digging, I resorted to child labor (see pics - even the 6 year old helped).
Step 4: Laying Out the Tanks
I did not get pictures of me cutting the tanks, but if you look at comments on pictures it should explain some of what I did to get them to this point.
After getting the tanks in the ground, you want to fill them with water BEFORE backfilling with dirt to prevent the dirt from pushing in on the containers. I buried mine with metal cages and all. I did this so I could use the sturdiness of the cages to help support the grow beds.
One of the picture comments explains the plumbing in a little more detail, but after I laid out the tanks, I used ¾" PVC for the pressurized plumbing (coming from the pump, a roughly 800 GPH pump that I will most likely upgrade in the near future for an expansion) and 1" PVC for my bell siphon down spouts and out spouts as well as gravity drains.
Bell siphon uses 1" down spout, 2" bell, and 4" media blocker
I used electrical waterproof connectors instead of water bulkhead fittings to go through the grow bed bottoms. The bulkhead fittings were $20, the electrical waterproof ones were $3. DO NOT use the electrical ones unless your grow bed is over the top of your fish tank. The electrical ones do leak slightly and it is enough that you would lose a lot of water over a day if it was not over the tank. I like mine leaking because it is a steady trickle that keeps the water aerated and if the power were to go out while water was in the bed it would slowly leak out into tank allowing water to aerate some until I noticed it.
Step 5: Finishing Up - Enjoy
I used gravel in my beds as it is readily available here locally and relatively inexpensive (I buy it by the truckload, about $200 for 5 tons which is enough to fill about 10 10" deep IBC beds. We use a 3 gallon bucket with drain holes to rinse the rocks as good as possible (nothing is perfect) before putting in to system to help get most of the sand, mud, and small (pea gravel sized) gravel out of the mix. We then take that 3 gallon bucket and rinse it heavily in a (roughly) 30 Gallon bucket filled with water - this helps things go by faster than spraying with a water hose. Also less water waste.
After everything is set up, leveled up and finalized, add some plants and some fish (or urea). There are different ways to cycle fish tanks - I choose using live fish, usually feeder gold fish so when I put my permanent fish in they can just eat the feeders :)
If you have any questions, please ask.
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