Vertical Pallet Planter With Automatic Water Cycling. No Watering!

About: I am a stone mason. My hobby is making new solar cooking and gardening stuff. I have used solar heat to cook soil for a couple of years. In mother earth news in January, i read that their compost expert does...
Check out the AMAZING airlift video!   I have checked (with a manometer) and about 0.2 psi has pumped water to over 6 ft high.  (It worked all night using 3/16 inch tubing).     The whole pallet planter thing works  great after a few modifications to the original idea!  As you work on them you discover things and adapt. Originally, it was going to be just one pallet standing up.  So now they are 2 pallets joined together (to get a decent 7 inch gap)  and the pallets have legs to stand on and the legs collect water in their "boots" to be recycled back up top again.  Also, the floors of each section now slope back.  The concrete on the bottoms of the "boots" is to prevent the weight of the pallets breaking the plastic buckets.

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Step 1: Concrete Shoes for the Good Guys!

This step looks hard but it really isn't.  If the plastic of the base of the bucket takes all the weight of the planter and moves, it will break and leak. So you need to make strong concrete round the base.  In this case, I made the concrete using wet masonry sand as a sand mold and a flower pot that is a bit wider to make the hole in the mold., I used a pallet with plywood under the sand and then a 3 to 1 mix of coarse sand and cement for the concrete of the foot.  So lots of pictures and a few image notes  to explain the steps.  The pictures are screenshots from a camera movie so not wonderful quality but its better than watching my youtube movies! As I write, they are curing, it is cold so it will be a while. BUT, I have already made one pallet planter to a slightly different pattern and that first one does not have the feet at all. I haven't used a sand mold in years but it works great. (Your sand has to  be just the right firmness and wetness.  If it sumps too easily you may have to add a portion of clay. (if you have clay!)

Step 2: Shoes Off!

Weather got really cold so shoes had to cure a bit longer.   Anyway here is the shoos been taken out

Step 3: Pallets and Preperation

There are many types of pallets,  Standard ones are about 4 ft by 4 ft. and up here in Victoria, many businesses are only too happy to get rid of them. 4 by 4 with decent solid 2 by 4's and one by sixes for the slats are ideal.   I have a video about how to break them apart with a long breaker bar, a tier iron  and a 2 by 4. This works great.  I also made up a tool to break them up. That is in the second picture.  It does a rougher job than the other method but it sure is quick!    It is 2 old brick hammers, a twisted fence post holder, and a waste piece of hollow steel tubing.  I wasted a lot of welding sticks but no metal!  when I made it. (My welder is an entry level one and just too weak to do decent welds) but hey!      $50 to $70 online + shipping     I also cut a groove in the front of one of the brick hammers (with a cut off wheel on the angle grinder) and it pulls out nails easy!  I am a stone mason and these were 2 hammers with broken handles.  It is cool to use them again!  The handle  bar is hollow and light, It has a plastic cap on top that I never bothered to take off.

Step 4: Putting Humpty Pallet Back Together Again. Trial Run.

My first one was a trial because the pallets were none standard size and there was not enough room.   Here is how it turned out.

Step 5: Bottoms of Planters All Lean Back

Water cycles through the system from top to bottom,  To prevent it dripping on each plant as it goes down, the planter bottoms lean back. This means that water gets directed to the back and drips down the back of the planter all the way to the bottom.  Everything gets watered but the plant leaves don't get splashed.

Step 6: Putting Humpty Together Again, for Real. (Having Learned From Experience?)

So, 4 by 4 pallets, with experience, Can I do it right?

Step 7: Airlift Pump, Non Standard, How Can I Make It Easy As Possible?

I was one of the main advocates for "the T-joint method" for airlifting water in windowfarms,  but the t-joint works OUTSIDE the bucket of water and works best with 18 inches or more of "submergence"  (this depends on your bubble pump specs).  I tried it in the buckets but their max submergence is only about 14 inches, and no room for the U below!  Can something be modified?

Step 8: Replacement for T-Joint. Lots of Testing on This Stage Before I Got It Right!

Low pressure airlift pumps are really simple,  you buy a an aquarium bubble pump (most will pump air 2 ft deep in water) and then you connect the air into a 1/4 inch internal diameter tube at the bottom of the bucket.  BUT, the air will often bubble out and not go up the tube at all.  With the T-joint method, I put the airlift outside the bucket and put a loop of tubing down  in a u shape to prevent backflow.  How can we get the air entry as low as possible and still prevent back flow without the  Utube?  
I ended up making something really simple, I punched a hole in a WIDER TUBE that fits snugly over the 1/4 inch internal tube and then pushed the air tube into it .   But you still get an awful lot of bubbling in the bucket!    The solution was very simple.  I connected a 10 inch section of 1/4 inch tube to the other end of the section of wide tube and stuck a piece of air delivery  tube in the end of that.
It is hard to explain why this works.   Imagine the inertia of that 10 inch tube of water.  by the time it is moving, and squeezing throught the tiny end hole,  the air is already going up the other  tube and carrying water into the pallet planter,!  next it starts moving the other way and inertia (again)  keeps it moving.    No bubbling, maximum submergence  and really even delivery of water to the plants!   This worked great!    

Step 9: Pumping Water

Here is the water coming up to the top and bubbling out of a 1/4 inch internal  tube  At the moment I have a little hole into a pop bottle to stop water gushes and the water just drips into the top portion of the pallet planter.  I am changing this so it drips onto some dolomite limestone first.  This will help make the water less acid and will also add some calcium and magnesium ions  to it.  All good stuff!!!
I hope.

Step 10: Here Is the Ideal Design, Just the Legs to Go in the Boots Now! Coming Soon!

So here it is. The first one was a trial to make sure it works.   Just have to put the concrete round the bottoms of buckets and it might be done by the end of this week! If you can imagine it being 2 of these sitting in 3 Buckets, that is what I am doing.
I had to play with the airlift longer than I expected to make sure it was reliable.   I expect only one airlift  tube up will be needed and the 2  (3 in my case)  buckets will be joined with a tube too.  I will probably have plastic sheet or some gutter pipe under the bottom most  planter section.

Step 11: Best Tubing Sizes and Getting the Tubing Dirty.

I have done a fair bit of testing over the last couple of years (and back to 2002 with pulser pump demonstrations) and the best tubing sizes for this type of airlift pump seems to be 1/4 inch or 3/16 inch.  In this case I use 1/4 inch internal diameter  tubing.  My battery operated air bubbler (that I used to demonstrate it on video) supplies  enough air to easily run 2 of these things through 1/4 inch tubes.
But my little mains driven bubbler supplies less air and can just barely run 2 at a time.   In that case the solution (if you want to run 2 planters) is to go down to 3/16 inch tubing.   3/16 is only 1/16 different from `1/4 inch in diameter but it isn't diameter that counts.  It is area and 3/16 inch tubing has just over half the cross sectional area!   3/16 tubing is slower but it only requires half as much air as 1/4 inch tubing!
Getting the tubing dirty.   New tubing will NOT work well for a day or 2. It might have a sheen or might be just too clean and water repellant. After a day of water going through it, it will work great.   Total difference.   What I do is just run it coiled around  on the ground and going straight back into the bucket for about a day.  That dirty s up the tubing nicely!

Step 12: Dilemma??? Air Tube From Far Away or Electricity Supply a Few Meters Away? Money Money Money!

It would be great to have the timer and little bubble pump in a shed right beside the greenhouse.  It is about 60 ft from a plug to the shed.  BUT $50 for cable, $50 to 80 for conduit and plugs brings things up over a hundred dollars and you still have to dig it in underground! so hundred dollars plus a lot of work!   My bubble pump and timer are in another shed with a proper electrical supply to code but it is 120 ft away!
Low pressure air would never travel that far through$30 worth of 1/4 inch tubing, would it? 

Step 13: The Little Pump That Could! and Success Breeds More Problems to Solve!

So, I laid down the 120 ft of  plastic tube from the little shed to the greenhouse and started her up,  Sure enough, it pumped the water, even at that distance!  Saves $70 and a sore back from a day of digging! But now, how do I divide up the air so that it runs 3 or 4 pallet planters?   Darn!    Another problem.

Step 14: Which Details Do You Want Next? Comment to Let Me Know.

I can bring you details about cutting the wood, or more detail about taking out the nails from the pallets  or finer points about  placing the airlift tubing?  or something else entirely.
I can even go in a slightly different direction based on a comment.
One point is that the water dripping through the system will take daytime heat and bring it down into the bucket. ( Water has a really high heat capacity)   (might be useful in the greenhouse to protect from night frosts).   I could measure that effect if asked.
Anyway, that is the deal.  If you want some part explained in more detail,  you have to ask.
I made the concrete bottoms today Thursday 9th January and have to let them set.

Step 15: Conclusions? Conjecture? If You Build It, People Notice? Puny Pneumatic Power Grid?!

I thought and  talked about this for years but never really had a good spot for it.  The design stage was a bit harder than I expected but nothing too dramatic.  Now we just have to see how it performs long term.
For me, the great thing that came out of it is the pneumatic power grid concept.  Lots of people make cool alternative power thingys but they are usually too small to connect to the electricity grid.  So they just give up! But this thing is just 1 psi. We should all be able to make a machine that makes 1 psi!  And 1 psi can travel fair distances.  We should be able to manage 2 or maybe 4 psi fairly easily.  Well, with 4 psi, you could have a pneumatic power grid connected to your neighbours?   If you have surplus, just let it go!  It is only cents worth of energy but for things like watering plants it is super valuable.  My "water pump" is just a 2.5 ft length of tube! in a throwaway plastic bucket!   Anyway, take a look at the concept in the diagram and see what you think!  Brian

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    18 Discussions

    Just a note that I have a "how low can you go" video that lowers the bar for airlift pumps!   This is extraordinary actually.  I ended up being able to pump water to over 5 ft high with just 3 inches submergence! And THAT means airlift could be used in a whole lot more places.

    4 years ago on Step 7

    Simply install a swing check valve to stop the back flow. Buy my manual $50 at Aquaponic Manual.

    1 reply

    No check valve is needed, the answer is in the next step. Note that the momentum of the water in the horizontal pipe causes the flow to be in only one direction and the constriction prevents a wasteful back and forth "vibrating" as it flows.

    Robert Chlebowski

    4 years ago on Step 8

    Hey, I"m having difficulties visualizing this. Could you explain where these tubes "Wide tube", "air delivery tube" etc are being connected. I attached a picture with how I see this step, hoping you could shed some light on it.

    air pump.png
    7 replies

    Hi Robert. I have a picture of something that works and I will attach it to this post right now. The length of wider tubing needed is about an inch. But I probably go 3 cm. I have found that a tube outside with the hole to let air in works better than a t joint inside. I am not entirely sure why but I think it is because it offers less resistance to flow at that point. Probably what is happening is laminar flow in the horizontal piece slowly builds up pace and then neatly keeps the water to air ratios very constant. Note that I have only used this to 14 inches deep (about 35 cm deep submergence). In theory, it should improve performance with deeper submergence too and probably with wider pipes. I will probably try it soon with half inch or 5/8 inch pipes in a rain barrel. So something like 10 to 15 mm diameter pipes. Rain barrels are about 33 to 36 inches deep 75cm to 90 cm deep. Not sure what a nice air speed and water speed would be with it. Ideally, I would love it if someone else tried it before I did! That would restore my faith in people! The experimental method only works if people experiment and confirm findings. This should be vastly superior to literary peer review. (Which is based on trust and proof reading).

    freshpaint gimp tiny airlift.png

    Hey thanks for the photo. Makes sense, I don't know why I was confused in the first place :S. Do you find the lifts work better with 1/4OD or 3/16OD Tubing? I Tried 1/2OD and only air was travelling through it, I even turned the air flow way down.

    Do you have any algae developing in the clear tubing?

    I've been doing small tests running something similar but with a flapper valve where the water goes in. In this case, imagine a flapper valve at the end of the 10" section at the bottom of the bucket. This is also an old experiment, since then I've developed something new.

    Here are my results:

    Static Head: 7.25", Lift water to: 65", Water Flow rate 0.22ml/s With air flow rate 17.24 ml/s. Efficiency, ~1.3%

    Static Head: 5.25", Lift water to: 65", Water flow rate 0.11ml/s with air flow rate 4.76 ml/s. Efficiency ~1.8%

    Static Head: 4.25", Lift water to: 65", Water flow rate 0.083 ml/s with air flow rate 2.94 ml/s. Efficiency ~2.83%

    Static Head: 3.5", Lift water to 20", Water flow rate 0.31 ml/s with air flow rate 1ml/s. Efficiency 24.33%

    Now, there are a lot more trials with varying performance and efficiency. I've just shown the results where I dialed back the air flow to get some water flowing with less and less static head (submergence). In the last trial I cut back the pumping height to 20".

    I'm wondering how to increase the efficiency without increasing submergence. Any thoughts?

    Hi Robert, thanks for doing all that experimenting and for sharing your results. Have you used the constriction at all or just your flapper? How are you working out efficiency? Are you going off the watts used by your air pump or are you just doing Mass by g (acceleration due to gravity) by height? (The potential energy formula) I suspect some error in the last number 24.33% because static head X air flow is 3.5 while water pumped by height is 6.2 which is over unity. (which is impossible). If you measured water flow correctly, however it is a really good sign. You used low submergence but I suspect you probably got useful work from higher pressure through the airlift pump. That is is great because ordinarily, higher pressure would cause blow back and even greater loss of efficiency. What is the ideal submergence for you? And the perfect pumping height for you? Have you tried splitting up the flow and using 2 airlift pumps from one source and pumping to different heights? Better I stop this post now before we both get lost!

    Perhpas my efficiency equation is wrong? All i'm doing is Output/Input (Note that my calcs are wrong ,my spread sheet was selecting the wrong values, I've corrected it now). I did another one which calculated efficiency based on work and pumping height form this website <<>>

    For the calc in the link, i'm selecting a trial where the pump did 0.0833ml/s of water for 2.9411ml/s of air. its pumping in 4.25" of submergance to a lifting height of 65".

    Electrical power: My air pump is 3.5 Watts, good to 2.1psi. In order for my system to work I have to dial back the air flow with a restrictor so that I'm using about 1/27th the maximum air flow (79.82ml.s is max air flow), so, i'm making a guess that in a nice world I could potentially use 1/27th the electrical power. So, for this trial electrical power is 3.5w / 27 = 0.1296 w = 0001737hp = Pa.

    Water power: The pumping height is 65" = 5.41'. The water flow rate is 0.0833ml/s = 0.001321 gal/min. Ps = (0.001321 * 5.41) / 3960 = 0.000001805

    (Pw / Pa) * 100 = (0.000001805 / 0.0001737) * 100 = 1.038%

    Now, granted that is different than a 2.33% efficiency of out/in, but I didn't want to set up my excel spreadsheet with more stuff. However, my calcs may be wrong for this particular application. Any equations for air lift pump efficiency I should be looking at?

    Hi Robert, to be fair you are using a 2.1 psi pump to produce about 0.3 psi or less. So you are really using something designed for a totally different purpose to produce your air. How efficient is it at producing air at 2.1 psi? So you need to get a tube that goes 58 inches deep under water to see. 58 inches under water is 2.1 psi. Measure the volume of air coming out. The formula can just be MGH for potential energy of the air. For instance if you are pumping 60 liters per minute of air to 1 meter deep, you are displacing 60 liters per minute of water. So the potential energy calculation is mgh m is mass in kg. And watts is energy per second. 1 liter of water weighs 1 kg. g is acceleration due to gravity. 9.8 meters per second per second. (we can use 10 for handiness instead of 9.8 so 1 by 10 by (1 meter high). That makes this a 10 watt power source. But of course, you probably need a 15 watt pump to do this due to losses and inefficiencies when you compress the air. My point here is that if you can calculate the efficiency of compressing air, then just assume this same efficiency in your "ideal world pump" that makes the very low pressure you need. So I think you need to be working out how efficient it is at using the low pressure air to pump water. And that is actually pretty easy. Efficiency of that process is just (volume of water pumped multiplied by height you pump to) Divided by (volume of air by depth under water that you are pumping it to). I think you need to make sure of your depth pressure with such low pressures. I think the best way is to let your pump go into an open bottom container that is in water to the required depth. All the excess air just bubbles out, and you get the amount of air and pressure that your airlift needs. Thanks Brian

    This is a helpful link. I made little vortex thingys, but my air flow was too small. I think you might only be able to measure effects in the 1/2 inch diameter tubing (1 cm to 1.2 cm diameter tubing) and maybe 5 to 15 liters per minute of air (at about 2.5 to 3 psi).

    I think there is a possibility of using higher pressure air with low submergence. There is a kind of fluidics "capacitor" called a vortex capacitor. If you put that where I have the constriction, there is a small chance that you get to transfer maybe 1/3 the air energy to it. I don't think it is efficient to produce 4 or 7 inches of air pressure, but it is probably fine if you are producing 14 or 16 inches of air pressure. I think it might be a good idea to produce something with, say, 6 inches, of submergence that can use 18 inches of air pressure. your vortex capacitor would both prevent backflow and gradually build up a powerful flow towards the joint where the air is introduced. I haven't really tried this. I made a few half hearted attempts to do it last summer. I think the vortex capacitor has to be either facing up or down, The center of the vortex enters into the horizontal tube. I had a quick look for links about vortex capacitors but didn't find any. They were used in fluid logic circuits. Fluid logic was used in the Apollo moon rockets and it is returning in nano technology applications. Brian


    6 years ago on Introduction

    I didn't understand the air-powered water pumping method. Do you have an instructable that explains it better, or can you add a diagram to explain it?

    4 replies

    Thanks I have a youtube playlist So check that out first, and I will put in a diagram soon.

    I think I understand now. The "pumping" tubing is thin enough that bubbles can't get smaller than the surface tension of the water allows, so they tend to float a few drops of water with them. It's a neat way to get a high rise with a low flow rate — I'm no expert on pumps, but with most hydraulic-based designs (peristaltic, piston, centrifugal) I seem to notice that maximum rise is correlated to water rise, so you need a higher-power pump to raise water so high.

    I added a new diagram to step 6. This has been working fine for at least 4 days now. The air bubble pump produces almost 1 psi about 120 ft away and it is still good to easily pump air 14 inches deep in the bucket. This 14 inches of pressure in turn can pump water just over 4 ft high into the pallet garden.

    Kind of sort of,, You just need to size the tube and air pressure and air volume right. My pulser pump has worked with "tubes" up to 1.75 inches diameter and it is a similar idea on a much bigger scale. If you look on the net for plug flow and slug flow you can find out more about how the airlift process works. The pumps are only making about 2 psi but they can pump (with the T-joint method) to over 10 ft high! No water pump can do that with 2 psi! With the tube in a bucket, and only 14 inches (max) of pressure head, they will struggle at about 6 ft but that is fine as we are only going 4 ft high. The great thing is it automatically adjusts, so if you are pumping to a lower height, you get lots more water. With the standard water pumps, their speed is set whether pumping to 2 ft high or 10 ft high.


    6 years ago on Introduction

    I learned that vertical agriculture is a concept that has a great reception in Europe since some countries do not have a lot of land dedicated to agriculture. Kudos on your use of pallets to start this great concept at home! Did you try siphoning the water to the top using atmospheric pressure?

    1 reply