Expandable Hydroponics System From Junk - Flood and Drain




I have been messing around with hydroponics on NO budget and HATE throwing otherwise useful things in the garbage, so being both cheap and EXTREMELY LAZY (I call it efficient), I decided to break a nail and this is what I came up with.

I've learned first hand and read that the most unreliable, but seemingly necessary piece of equipment in most systems is the water pump. If you want something reliable, you are going to have to spend money and be prepared to maintain the pump and nutrient delivery system. Too much work for a potentially catastrophic failure if you ask me.

I found inspiration in an instructable that I can't seem to find any more. I'm sure it was called "The World's Simplest Flood and Drain System". I would like to apologize to anyone else that I do not mention or refer to due to my incompetence, but if you see any similarities please do provide links in the comments as I do not claim to have many original thoughts.

The air pump has become a staple component in most systems for various reasons. Moving water with air makes complete sense to me while solving several issues and being cheap, reliable and easily serviceable. Pump maintenance is algae free and time will tell just how reliable.

Next, the system had to be sort of "free",so this meant parts that are common, cheap or reclaimed. Enter my friends, the pop bottle the milk bag and their goofy sidekick Aluminized Bopet (chip bag to most).

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Step 1: What You'll Need

1 ea aquarium pump
1/4 inch air tubing as required
3 ea 2L pop bottles or more as desired
1 ea pop bottle cap(reservoir cap)
2 ea Sunlight dish detergent bottle caps or pop bottle caps(planter drain)
3/8 inch inner dia. vinyl tubing as required (approx 2 ft)
1 ea 3/8 inch nylon plumbing TEE adaptor
1 x 3 length of wood or equivalent planter support
Growing medium (I use pea gravel)
Milk Bag optional
Chip bags as required
1 ea elastic (aka rubber) band

7/32, 3/8, and 1 1/4 inch drill bits (that's 1 and 1/4 inch)
Hot melt glue gun.......maybe

Step 2: Reservoir Lid

Drill 1/4 and 3/8 inch holes in lid as shown. Be careful to keep holes as perfectly round as possible and spaced to allow for bottle threads when screwed on.
Cut ends of 1/4 inch and 3/8 inch tubing on an angle for easier feeding through the undersized holes.
Feed approx. 12 inches of the 3/8 inch tubing and a small amount of the 1/4 inch tubing through lid as shown.
Screw cap onto one of the bottles.

Step 3: Planter

Cut the bottoms off the remaining two bottles. Drill small holes in the bottom pieces, invert and place inside the top pieces as shown.
Remove the "slidey valve thingy" from the detergent bottle cap, revealing the nipple over which we will slide the 3/8 inch tubing (not easy). The cap just happens to be perfect for this and fits securely over the 1 inch pop bottle threads.
Alternatively, any bottle with a nipple cap can be used as the planter itself as long as the tubing can provide a seal over the nipple or the tubing can be fed through an undersized hole in a cap w/o a nipple, also shown.

Step 4: Planter Support

Drill 1 1/4 inch holes through a piece of 1x3 wooden shelf or other suitable support, spaced as desired or required for plants.

I will leave the supporting structure construction up to your imagination as my skills are very limited and I do not want this to become a lesson on "How NOT to Build a Shelf". The simple structure that I built is very visible in the photo.

Step 5: Removable Planter Bag - Optional But Handy

Poke many holes in an empty milk bag large enough for good drainage, but too small for growing medium to escape. A drywall screw worked for me.

Fill with medium and place in finished unit.

Handy for transplanting or system maintenance. It is also MUCH easier to see the water level due to the air space around the bag.

Step 6: Assembly

Place assembled reservoir bottle into secure position and secure planters in an inverted position, several inches above the reservoir (this allows space for interconnecting the reservoir and planters). Connect the 3/8 inch tube from the reservoir to the nipples on the planters using remaining 3/8 tubing and TEE connector as required. Try to keep connections as short as possible, kink free and above the reservoir for proper drainage.

Connect air tube to aquarium air pump.

Fill reservoir through planters, if desired or by simply unscrewing cap and removing the reservoir bottle for maintenance. Do not overfill reservoir, it will be plenty once the plants are added.
At this point it should be fully assembled and ready to test. Test by turning on air pump and check for air or water leaks. Fill any leaks with hot melt glue.

Step 7: Operation

When air pump is on, the nutrient will be forced up into the planters until the pump is turned off. The nutrient will then return to the reservoir through the help of gravity at a rate determined by the back flow of air through the pump and any leaks. Note: Air leaks are not necessarily bad, but will limit max height the water can be pumped while allowing for faster draining. Small amounts debris are easily flushed harmlessly to the bottom of the reservoir during the drainage cycle.

My timer is set to 2 minutes, but I let it run longer in the video to show what happens when the reservoir empties.

No check valve is required as it can't siphon through the air pump AS LONG AS the reservoir is not overfilled.

There is no overflow protection for the planters so a maximum level of nutrient will need to be established once filled with growing medium. This can easily be marked on the reservoir with the elastic band. Min/max levels should both be established this way. Cannot be seen well in video, but there's a max limit.

Put reservoir and planters in inverted chip bags to prevent algae growth. Double up if necessary. It works great. See DWC unit in finished system photo, but that's another story.

Due to the simple operation and modularity (if that's a word) of this system, it can easily be modified or expanded upon with ease to suit your space or container needs. PSI and volume are your main restrictions.

I apologize for the poor lighting in the video, but I have removed the bag so you can see the progress. Prepare to be bored! Especially by the last minute, forgot to edit that out, sorry.

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    66 Discussions


    7 years ago on Introduction

    What a cool idea! Have you (or anyone else) been doing this for long? What type of aquarium pump do you use? How long has it lasted? I'm worried about the pump diaphragm rupturing. How high can you lift water with this? Thanks!

    1 reply

    I've had a system, very similar to this one, operating for about four years now, with the same plants you'll see in these instructables. The plants are doing very well (bamboo and Devil's vine) even with major stressing/negligence on my part.

    It uses a Hagen 802 double pump, without any failures.

    I'm not sure how high it can pump, but the video kinda says it.


    You're welcome.


    10 years ago on Introduction

    Can you spare some details about your timer setup? I've found some round one on/one off timers, and am not sure what to look for for a setup that goes on and off three or more times daily. Thanks!


    11 years ago on Introduction

    I think this system HAS to be a little loose. Just set one up, and the water I used to test it just plain will not drain back into the reservoir! This picture shows anti-siphon valves, because I had them laying around, but even without them the water will not drain! Any ideas on how to make sure the air pressure can be released when the pump is not on? I haven't check for valves that perform this function, but if anyone has ideas let me know! Great work wiley!

    16 replies

    As mentioned previously, there is a good chance that your air pump has an anti-siphon built in it (this is because people will still put their pump below the water level - even though the instructions say to never do this without a check valve - so that if the power goes out as siphon wont be created). A lot more of the higher quality ones are doing this now.


    Reply 10 years ago on Introduction

    Dont know if this problem has been solved yet, but sometimes aquarium air pumps have built in anti-siphons. You can tell by blowing into the hose while it is connected to the pump, If you cant, then it probably does. alternative-innovation.com


    Reply 10 years ago on Introduction

    What works is if you take the hose off the air pump when you want it to drain. That is what I do.


    Reply 10 years ago on Introduction

    I don't know how technical you want to be, but a low or middle voltage solenoid valve would allow for this. If the system were tight, an added valve tied into the time would work. Tie it in so it stays energised while the pump is on and it will open and drain when it goes off. A time delay would allow it to keep the fluid to stay up longer if you wanted it to. If you need an electricial drawing, send me an email and I will make one up for you.


    Reply 10 years ago on Introduction

    Yah, I think that is more work than I am up to. But I did find out there is a hydroponic store in my town, so I might check that out. Good suggestion!


    Thanks. Excellent setup. I am humbled. It would slow down the fill rate and limit the height that it could push, but I tried adding a 2 way control valve to create a controlled leak to speed the drain cycle. It worked, but I found it unnecessary as my air pump allows back flow. You could try another pump, but I would introduce an air leak somewhere above the waterline, hopefully a controlled one first. I would leave the anti-siphon valves out altogether because it can't siphon back, especially in your setup, and they would add slight resistance which may be unwanted.

    gomiboywiley coyote

    Reply 10 years ago on Introduction

    I'm going to try this with my daughter's 4th grade science class, and as we'll be building it in the classroom, I'm not going to have much room for tinkering with it. Nobody has volunteered a pump yet, so if mine doesn't allow air backflow, how large a hole do you think I'd need in the reservoir or air hose? I'm hoping I'll have some spare bottles, but won't have much spare hose handy if I screw it up. Thanks!


    Reply 10 years ago on Introduction

    Sorry to add more - I'm planning on building with a single reservoir, pretty much straight from the 'ible, so I won't be needing to sync anything. Thanks again for any and all advice.

    wiley coyotegomiboy

    Reply 10 years ago on Introduction

    You may want to consider something like this for a single reservoir system. I know it's not pretty, but it's a work in progress.

    wiley coyotegomiboy

    Reply 10 years ago on Introduction

    Mine is a Hagen Elite802. If you can't find that, make sure that it does not have anti-siphon built in and you should be fine. Try to do all tinkering on the bottles or caps themselves as they are easily replaceable. The tiniest of holes near the top of the bottle should work. The hose is a valuable resource, so try not to mess with it. It really is so easy to build, I would recommend throwing one together, or at least a partial system, in advance and tinkering with it, so your not going in totally blind.


    Just an update. I tried putting a very small hole in the cap, the smallest drill bit I could find, to no effect. It seems that even that small of a whole lets out too much pressure. I enlarged the hole and put in a screw, which I can adjust in order to change the amount of pressure in the bottles. Not quite perfect, but as my pump doesn't let air back out, it works for now. Still working on what to plant in these, as no stores have seeds anymore.


    Excellent. Whatever works. I've run into similar problems with my pump where the water column was lower and it drains really slow. I've used cheap, 99 cent, plastic 3-way control valves with the variable tap open quite successfully. Here's a pic. I also included a plastic gang valve($4.95) that would work as well. Both left over from old aquariums, but available at any aquarium supply store.

    Control Valves.jpg

    Thanks! Great artists steal. I just cut a little notch on the side of the airline hose hole in the cap. Works fine, but its hard getting the two reservoirs to sync, and I ran out of caps. I'm a high school teacher though, I can get plenty of those. My pump doesn't allow air back through, so the siphon valves aren't hurting anything really. At least I know where they are if i need them. Now I just need to figure out how to start plants going in there!


    I was thinking, you could experiment with hole sizes near the top of the 2L reservoir bottles to sync them. The rigidity will give you better control over flow rates and they're easiest to replace if you screw up as well. By varying the hole size in each reservoir, you could approach equilibrium. or for the less patient You could use control valves. If you had a gang of three you could use two to sync the reservoirs and a third as a controlled rate leak or vent. I just filled the bag with pea gravel and old aquarium gravel, threw some mung beans just under the surface and they grew. The cats made short work of them though, once they found them. I didn't think it would be that easy, but that's probably because they were mung beans.


    Reply 11 years ago on Introduction

    you could also simply add another water pump to pull all the water out instead of pushing it in this way you could extend the length of time the roots are exposed to the water / nutrient solution this would also have to be on a separate corresponding timer