Building our hydroponic greenhouse using IBC totes!

Being an avid chess player has taught me to think as many moves into the future as possible. So two years ago when I came across these food grade IBC totes for cheap on Facebook, I knew they would fit in to my future plans some how. Future options included water storage, irrigation, or even fire control. I had also started my rabbit hole research into types of container gardening. While I didn’t know exactly which slot they would fit into, I knew they were coming home with me.

Fast forward to September 2022. I have my greenhouse erected, and enclosed. The doors are hung and while still a work in progress, the time had come to move forward with getting some things growing! I had been experimenting with different types of container growing by now and had it down to two types of planters. The first was self wicking planter boxes. The idea here is to create a well of water under the soil and allow the soil to wick the water up to the surface. I’ve had great success with this method in 5 gallon buckets and blue 55 gallon barrels. My initial plan on these totes was to start with the wicking tub idea then if need be move on to second idea of using them for hydroponic tanks. My plans for the self wicking planter and the hydroponic tank used the same layout and plumbing so I moved forward still undecided.

I started by taking my sketches off paper and getting a real world visualization of how the tanks would be arranged. Using empty feed bags and a tape measure, I laid them out to represent the rows of tanks. Imagined working in each tank, maybe moving our cart in between each row. My greenhouse is 30′ by 30′ with 6 5′ bays. My original plan was to put a row between each bay, but the reality was that it was just to crowded. I settled on 5 rows evenly spaced, two tanks placed end to end.

The IBC totes are encased in a steel frame with a built in pallet on the bottom. Since my plan was to cut each tote in half, I needed an additional pallet to even up the top half with the bottom half. I found plastic pallets on Craigslist that would give me both long term durability and the height I needed. The first step was to get the gravel bed level. Using the pallets as placeholders, I was able to use my 4′ framing level to get everything set.

Once the gravel bed was ready, I pulled everything out and laid down the ground fabric. I wanted the ground fabric over the top of the gravel bed to keep dropped seeds from sprouting. Also, while its not my nature, my vision was to have a super tidy greenhouse! 🙂

I’ll write up a different post where I go over the process of cutting the IBC totes into two pieces. At this point I am still pondering between the two options however something was giving me the confirmation I needed while I was working. If you look to the right of these photos, you’ll see 55 gallon blue barrels. In my past experiments, I used the Kratky Method for growing cucumbers. Based on the great success I found using that method, I set up a row of test barrels with peppers, zucchini, squash and more cucumbers. Everything exploded and was growing like mad! Seeing the results of these barrels I opted to move forward with the second option and go full steam ahead and set these tanks up as hydroponics.

Blocking sunlight is key for keeping algae at bay. This also helps promote better root growth. From my research I found most people doing this set up either painted the exterior of the tanks or wrapped in black plastic. I happened to have a roll of black tar paper that was needing a purpose. I cut strips to fit between the tank and the cages. Only had a few tears which were easily repaired with black gorilla tape.

In the countless hours of researching hydroponic options I settled on using the Kratky Method. One of my main goals for the greenhouse is to have it as grid independent and low maintenance as possible. Most hydroponic systems require pumps to move the nutrient solution and oxygenate the water. Pumps require electricity, if the power stops, the system fails. I opted for the Kratky Method for its simplicity and zero reliance on pumps and electricity. After blacking out the tanks, I needed to frame the tops. Framing them off gives them a very clean look but mostly will give me a way to support and contain the rigid foam boards where the net pots will be set. For the framing I used 1″x4″ pine strips which I primed with Killz primer. Its late September and I’m up against the clock so I’ll come back and get these painted later. I’m using 2″ net pots for the lettuce and spinach so I went with 1/2″ rigid foam boards. This thickness helps get the net pots closer to the nutrient solution. I wrapped black gorilla tape around the edges to keep it tidy and extend the life of the foam.

Having never done this before, and not having a lot of resources to go off, I opted to use 2″ net cups, in staggered rows, 8″ apart. A 2″ door hole drill bit run in reverse cuts the foam board cleanly and is a perfect fit for the cups. The first 2″ net cups I ordered were very cheap and had a super thin rim. I returned them and found these heavy duty cups with wide lips. I am super happy with them!

Since we are using the Kratky Method, we are following his nutrient solution recommendations and using a combination of MasterBlend 8-16-36, 15.5-0-0 Calcium Nitrate and Epsom Salt. I will write up a full post on the process we use for this. We just call it Gatorade, giving the plants all the electrolytes they crave. 😉

Its nearly the end of September and summer has started to fade into fall. I’m under pressure to see if I can get some kind of harvest in these initial tanks. Also, since I don’t have my wood stove installed into the greenhouse, I don’t have a heat source. The clock is ticking. With that, I’m only going to start with three tanks. One tank will be lettuce and two tanks will be dedicated to spinach. I had starts from a different project ready to go. I transplanted them into the net cups using perlite as the support medium.

That wrapped up my initial hydroponic tank set up. I had other things on my fall to-do list and had to move on. Its now 3 months later, New Years Eve 2022 as I write this. We have had typical Pacific Northwest weather with one brief week of 14 degree weather and a few days of freezing rain. I wasn’t ready to lose the incredible results of this just yet. I setup the remaining foam boards around the main tank and added a heat lamp. It worked and things are still rocking. If you’ve made it this far, make sure to watch the video’s in my gallery that show all the results of our efforts.

Here’s to a much better year on 2023!