Due to the response of the last hydroponics system Flood and Drain from Junk, I figured I'd get this down while it's hot in my head because it answers some of the questions. Please do refer to the link above as it explains much of the theory.

I've simplified the system further to lend itself to massive expansion. The planter bottle has been modified to eliminate the need for interconnecting hoses as well as make it accept ANY airtight, and I recommend RIGID, reservoir. It sort of reminds me of a mosquito and works much the same way. As the air pump increases the pressure inside the reservoir, the nutrient sol'n is forced into the body of the mosquito. When the air pump is off, the resulting lower pressure allows gravity to return the nutrient to the reservoir and empty the body of the mosquito.

Modify as required and desired. For simplicity, I've quickly built a two planter unit out of stuff I had on hand and have ignored any efficiency issues. This is more to show the concept and although it "works", this one will not be used as a unit itself. I have also not filled the planters with bags of grow medium and plants for this same reason.

It'll be real short, I promise.

Step 1: What You Need

One airtight reservoir
One air pump
1/4 inch air tubing as required
Two pop bottles
Two 12 inch pieces of 1/2 inch CPVC pipe with one end cut at an angle
1 ea 5/8 inch drill bit
1 ea 7/32 inch drill bit
1 ea 9/16 inch drill bit (please pretend that's what's in the picture)
One drill (not shown)

Step 2: The Mosquito

Drill 5/8 inch hole in lid of any plastic beverage bottle. I used 500 ml pop bottles for this one.
Cut the bottom off the bottle.
Place bottle upside down on pipe.

It kinda resembles a mosquito, don't ya think?

Step 3: Reservoir

In the lid, drill one 7/32 inch hole, through which, we will feed the tip of the air hose.
Also in the lid, drill two 9/16 inch holes through which we will gently force the pipes. Works best on warm plastic.

Any reservoir will work as long as the pipe can reach the bottom. The more rigid, the better.

Sorry, forgot to take picture.

Step 4: Assembly

Gently drive the angled end of the pipe through the undersized 9/16 inch holes like a hypodermic.
Insert tip of air hose through the undersized 7/32 hole.
Fill with water and turn on.
Seal any leaks as req'd.
Adjust min/max and timing as req'd or desired.

It was at this point that I realized that the more rigid the reservoir is, the better. I'm thinking 4" drainage pipe.

Fill planters with a grow medium. I would use a small chip bag with holes as a removable, grow bag "sleeve", but you can use any medium as long as it cannot flow through the pipe and into the reservoir.

No boring video. Trust me, it works.
Can you explain how you made the second rigid tank? It looks like drainpipe. Really good instructible, thanks. I hadn't grasped why anyone would go for airpumping rather than water pump before reading this, but of course it means you can feed many chambers off one pipe/ pump.
It is drain pipe, that has been capped with heat shrunk 2 liter pop bottles.<br><br>The reservoir, itself is here.... https://www.instructables.com/id/Modular-Hydroponics-Low-Profile-Reservoir/<br><br>
Interesting, but I would still use a water pump. Of course a water pump can fail, but the airtight seal (which the system relies on) would be much, much more prone to failure than even the cheapest aquarium water pump.<br />
The systems actually do not drain if the seal is too airtight, and require some leaks, either by chance or intentional, in order to work properly.&nbsp; If the leak is too big, it will fill too slowly, if at all.&nbsp; If the leak is too small, it won't drain.&nbsp; It's a fine tuning thing.<br /> <br /> I don't, however, recommend building this unit as shown.&nbsp; It was more of an experiment.<br />
I'd also like to add that a version of the &quot;experimenter&quot; has been running failure free for over a year now.<br />
interesting, interesting... What about if it goes too far and starts spilling, I don't want to babysit it for 5 minutes... If I was going to babysit it, couldn't I go even greener and use a footpump for an air matress?
get one of those giant soda bottles
Good point, but no. Hmmmm...you could use an air bladder (aka strong plastic bag) somehow as a limit switch inside the reservoir. Preset displacement. Greaaaat......here we go again. Anyway, you would put only enough nutrient in the reservoir to fill the planter to a max level, at which point bubbling would start. The bubbling will quickly prompt you to turn it off, buy a timer or setup a limit switch type gizmo thingy. I opted for a Christmas light timer. I may have to invest in a foot pump over the Holidays. Fine tuning of the fill rate can be achieved either through varying the airflow into the reservoir via a control valve on the air line or by making holes in the system above the water line, which would be highly unrecommended, but effective.
how bout one of those blowoff valves, like on a portable air tank? do they make them in that low of a pressure?
I've tuned it using an adjustable air valve using a small self tapping screw. If you introduce an adjustable leak, you can tune it to a certain level, but I'm not sure how time would effect the process, with nutrient level changes and clogging of the hole over time. To actually answer your question though, I'm sure you can find all kinds of miniaturized components for everything these days if you know where to look. I do not.
me neither. The bigger the diameter, however, the less of an issue clogging would be. ...however there are seizing issues the lower the pressure gets. How bout a crude cork gun approach? Use a champagne cork(mushroom shape)to stop up the hole on top. Put a stopper so the cork doesn't completely blow out.. I'd drill out the center halfway down and add fishing weights accordingly. Bake the cork to dry it, then soak in glycerine or Kroil to lube. I'm poor, so I always approach economically. Or maybe I'm completely out of my mind... Just glad to contribute.
I like it. I'm approaching these designs as though I have $0 to spend, so that's exactly up my ally. Thanks. Why would anyone want to be confined to their "mind" anyway.
i'm going to prob make this my first instructable, assuming i can find a more general version for multiple uses. i just have to think about what else it can be used for. if u wanna try it and post it, more power to you. if u can think of other general uses, plz help. Keep building!
IMHO if you build it, they will come. People will find uses for it and/or modify your idea to suit their needs. What better use than growing food and for "free". I kept seeing people break down the cost per tomato/pepper to justify the cost of the systems they had purchased or built. I'm just taking that a little bit further, if I can.
This design has me thinking. I dislike getting the litter in the buckets because they're that plastic type "5" and my recycling center does not take it. But the bucket is a better "deal" price wise. This gives me something to build with them if I can scrounge up an air pump.
Good luck. Soft plastic containers will bulge and try to become spherical, creating leaks. Be prepared to reinforce.
I'm curious if anyone has tried heating the plastic containers. With the Keep The Bottle contest going on I was inspired to try some PET sculpted bowls and the plastic becomes smaller but more stiff. I'm unsure what type 5 will do if I hit it with a heat gun.
Thank you for this instructable - I have been wanting to make a hydroponic windowsill garden for a few months, and was looking at the expensive kits before I came across this. Your design is much more elegant (especially air pumps vs. water pumps), and I like re-using normally discarded materials. I'm going to build one in the next few weeks, I think using a 5 gallon bucket. I'll likely use c-clamps to keep the lid secure with the air pressure, and can fashion a gasket for the seal if it comes to that. I'm curious, though, about Step 4, where you say "seal any leaks as req'd". What have you found to be the best way to seal the leaks, and where are the problem areas? I'm curious if hot glue will work, or (more preferably) if rubber gaskets can be obtained in the correct size. Do you have any concerns about chemicals from hot glue / sealant leaking into your nutrient water and depositing in your plants? Again, thank you for the great instructables!
Elegant... I like that. Thanks. The air pump thing just seemed to be the easiest way to move large amounts of water with minimal effort and maximum reliability. Time will be the judge of that. I use hot melt glue whenever possible, but have found that it doesn't bond well with some plastics, particularly the kind the pop bottle lids are made of, and will leak over time. Grommets seem to work well and I imagine silicone sealant would work as well. The problem areas would be the lid seal when the container bulges under the pressure and any holes made by you. Grommets seem to work best in my experience and also allow for movement. The biggest problem, I think, will be the bucket, but it may be easy to overcome. You'll know what your problem areas are about 30 seconds after turning the pump on. I don't really have any concerns about chemicals leaching, but that does not mean that I shouldn't. I'm avoiding solvents and the like purposefully, partly for that reason. The plastics themselves are probably the biggest threat, in my humble opinion. Your welcome and thanks again.
could you please take a pic of where to drill the holes in the air hose so the rest of us can understand what it is that you are talking about...step 3
Sorry. I'll edit that to make it clearer. The hole is actually in the lid and you feed the tip of the air hose through it. This allows the top of the reservoir to fill with air, resulting in the nutrient being forced up the "straw" and into the planter(upside down bottle). I've included a pic from the unit above, but I would recommend the setup pictured further down in the comments, with the horizontal drainage pipe as the reservoir, if you were to build one. The soft plastic reservoir is a problem.
Could you please be a little more specific?
I don't know what this is supposed to do or be.
It's a simple flood and drain hydroponics system that uses air pressure rather than a water pump to "power" the flood cycle. This modification allows for a greater # of planters over my first design, referred to in the intro. I left out a lot of redundant info from the other instructable, in error, trying to keep it brief. Hope that helps. If you have any more questions, please do not hesitate.
I'm sorry that i didn't reply yesterday I just barely found your comment because Annoying Brother #1 barely let me have the computer because he is still asleep.
Ahhh...annoying brothers...the sleeping kind are best.... They don't see it coming!!!
what size air pump are you using?
It's a Hagen Elite 802, double pump. The single equivalent, since I only use one side for this, would be the 801.....I think.
why not make use of both outlets and double your air pressure by joining together as one tube? The benefit would be more oxygen to the roots right?
I use the second to drive some air stones in two Deep Water Culture experiments (which seem to be doing well on the same cycle as the Flood and Drain). The single pump provides lots of pressure for any load I've placed on it. In fact, compared to driving air stones, you could grow many more plants off of a single pump using this method...I think. I would add additional pumps for redundant backup in an actual system, though. The oxygen to the roots in a Flood and Drain system is primarily provided by the draining water pulling in fresh air to the roots on each cycle. I don't believe it is an issue to have the nutrient oxygenated or not in this system.
I wonder how well this system will work for aquaponics
I have wondered the same and I imagine the biggest obstacles would be a sealed aquarium and fish that could easily handle whatever differences in pressure were encountered. Since the fish would require oxygen, it may be necessary to have the pump running constantly. A "vent" could close and open to supply the necessary changes in air pressure, rather than turning the pump on and off...just a thought. It would one of those long, drawn out projects just to see "if"....... Sounds good to me!!
I know I'm flogging a dead horse here, but I just had to show it....sorry.<div style="margin-left:15px;"> <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/iXldj2b0WsA"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/iXldj2b0WsA" type="application/x-shockwave-flash" width="425" height="344" wmode="transparent"></embed></object></div><br/><br/>Notice that unopened bottles, instead of planters, do not fill and can be used as &quot;blanks&quot;. This allows for building &quot;potential&quot; (for lack of a better term) into designs without the need for extra nutrient solution.<br/><br/>It drains really slow, compared to the other design, but it does eventually drain. I've added a control valve to speed the drain cycle, which also slows the flood cycle.<br/><br/>I promise, no more on &quot;this&quot; subject for a while.<br/>
Here's a swarm of Mosquitoes. It works great, but drains much slower.
I have heard of hydroponics, but never read up on it. Your plans are inspiring me to do so! BTW, the mosquito is a much cleaner and hence, less daunting proposal... VERY COOL! What exactly is the "nutrient", is this simply liquid fertilizer, e.g., MiracleGro? That looks to be a pretty significant (e.g., bigger than a garden variety aquarium) pump. If I do this, I will be using a similar (i.e., different in brand of kitty litter) reservoir; could you spec the pump you used please?
I do recommend reading up on it, there is lots of info out there. Everyone says you have to spend money, though. I think they're selling something. I am just a beginner, not wanting to spend money on something that will fail and trying to solve prob's before I waste a growing season. The nutrient is a generic, "total nutrient" sol'n. Miracle Gro apparently lacks some nutrients, so I do use it as a low cost alternative. The pump is a double pump, hence the size, and it is a Hagen Elite 802. Cheap and reliable. Although it will work, I DO NOT recommend the kitty litter reservoir as the plastic is too soft and will require reinforcement and leak proofing....in my own limited experience. It bends under the increasing pressures. Something rigid and as low profile would be best...I think.
Thanks for the reply! I'll consider the comments on kitty litter container, but don't think I can resist the urge to try to to use it (I was thinking of caulking/melting shut the large side of the hinged top, for more strength. The pump name/model is much appreciated!
No problem, happy to be of service and Good Luck!
it is nice
Thanks and I'll assume you mean the concept.
will see my instructable? my address is<br/><a href="https://www.instructables.com/id/how_to_make_your_own_pet_easily/">https://www.instructables.com/id/how_to_make_your_own_pet_easily/</a><br/>
Interesting concept. I had a friend who used a metal 55 gallon drum and used compressed air from the compressor in his basement workshop to "blow" the water outside. Ken
i am so sorry, but this is the lowest rated instructable on the site. out of pity, and like for the idea, i give you 5 stars.
Thanks. It's a small price to pay for progress. It's more of an idea thing, though. I apologize for my sloppiness but I felt that if I had have been more precise in any construction details, the "idea" would have gotten bogged down by "my" details, redundancy and time spent looking for drain pipes and grommets and stuff that would not necessarily be relevant in anyone else's set up. Did I mention extensive use of run-on sentences as well. Some find that annoying. I was worried that they were too wordy or specific over otherwise mundane details that are best left to vagueness.

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