Even Simpler Flood and Drain System - the Mosquito

Intro: Even Simpler Flood and Drain System - the Mosquito

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.



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    45 Discussions


    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.

    1 reply

    It is drain pipe, that has been capped with heat shrunk 2 liter pop bottles.

    The reservoir, itself is here.... https://www.instructables.com/id/Modular-Hydroponics-Low-Profile-Reservoir/


    8 years ago on Introduction

    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.

    2 replies
    wiley coyoternearhoof

    Reply 8 years ago on Introduction

    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.  If the leak is too big, it will fill too slowly, if at all.  If the leak is too small, it won't drain.  It's a fine tuning thing.

    I don't, however, recommend building this unit as shown.  It was more of an experiment.


    9 years ago on Introduction

    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?

    8 replies

    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.


    9 years ago on Introduction

    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.

    2 replies
    wiley coyotecynvision

    Reply 9 years ago on Introduction

    Good luck. Soft plastic containers will bulge and try to become spherical, creating leaks. Be prepared to reinforce.

    cynvisionwiley coyote

    Reply 9 years ago on Introduction

    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!

    1 reply

    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.

    logic bomb

    9 years ago on Introduction

    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