Hydroponic flood-and-drain bin system

thingiverse

A series of inexpensive bins are connected to a central reservoir to form a hydroponic garden system.This is designed to work with Aerogarden pods but can be made to work with 2" net cups. Timer pumps draw water from the reservoir and pump it to the top of the pod or net cup. The water drips down over the roots and fills the bin. When the water level in the bin reaches the height of the spigot, an automatic siphon effect kicks in, draining most of the water out of the bin through the spigot. This water then drains back down to the reservoir. This prevents the bin from staying full of stagnant water that promotes root rot.This is a variant of another system I designed which used isolated bins and no reservoir: https://www.thingiverse.com/thing:5160290A key element to this system is the auto-siphon.Please refer to the included exploded diagram.This video shows the auto-siphon in action: https://www.youtube.com/watch?v=-f2A8NZCzCgThe U-shaped siphon draw tube must be airtight to ensure a siphon can form. Any air leakage means it will not work.I printed this using ASA and dipped the finished part briefly in acetone to seal it, hanging it to dry from some wire. The result is a shiny, sealed surface. This worked really well and the ASA is holding up over time.Wrap the tapered portion of the draw tube in teflon tape before pressing snugly into the backside of the spigot, and ensure the tip of the draw tube is positioned in the bottom corner of the bin so that it can suck as much water out of the bin as possible.On the outlet side of the spigot, a siphon insert is pressed into the tip to restrict flow.This is important because the water level in the bin rises too slowly to initiate the siphon effect unless the flow inside the spigot is greatly restricted.The insert should be printed in TPU or other flexible material.Several STLs of increasing length are provided. Use the length which works best with whatever drain manifold you come up with. Adjust your scaling to get a tight fit. This does not need to be airtight, but you do not want it falling out of the spigot. You can raise the back end of the bin to improve the siphon draining effect even further. I used a 1/2" thick wooden board that I got for a few bucks at the hardware store.The design of your drain system will depend on where you are putting the bins. I am using an 18x48" standard wire rack shelving unit (https://amzn.to/3doEh1U). I made my manifold out of 1/2" PVC. Several lengths of PVC drain manifold hanger are provided which work well with most wire shelving. The number in the STL corresponds to the inches of offset. Use one that is 0.5 inches longer than the other to provide a slope and keep stagnant water from remaining in the manifold. Note that you do not want to seal your bin spigots into the manifold. The water draining from the spigot should fall through the air and into an opening of some kind on the manifold.Your reservoir can be anything. I used a Home Depot bucket. Cut a hole in the lid and run your drain manifold back to it. I recommend using tubing that is no smaller than 1/2" inner diameter to avoid drainage issues which can cause your manifold to overflow.Printed parts provided include:Draw tube - requiredASA recommendedSiphon insert - requiredTPU/flexibleAerogarden adapter 2 inch drip feed - required if using Aerogarden podsPLA or other rigid materialThis has two ports where you can insert the drip feed tubing, with strain relief tabs that allow you to zip-tie the tubing in place and prevent it from coming loose. The tubing that comes with the pump linked in the Google sheet below will fit these ports perfectly. You only need to use one port, but two are provided in case you want extra flow.Ikea bin clip - recommendedPETGThe latest version of this has holes so that you can tie string to it. This is helpful for providing support to top-heavy plants as they get large, such as chili peppers. Put one of these clips on each side of your bin, then use them as tie-off points to keep your plant from falling over.PVC drain manifold hanger - optionalTry this if you are hanging a 1/2" PVC drain manifold from a wire rack shelfPurchased parts required are listed on this Google sheet. The green highlighted column indicates which items are required for this version of the system.https://docs.google.com/spreadsheets/d/140NJgnDm5aTWNqSGU7r5p_UNfO09xHHKGXLjrYhKuko/edit?usp=sharingCheck out this video where I show how to cut holes in the bin, bin lid, and install the spigot. You will not need to cut nearly as many holes in the lid if you are building this variant of the system, so be sure to look at the screenshots on this page and understand what you are building rather than blindly doing everything you see in the video.https://www.youtube.com/watch?v=gUQ236HlwN0If you do not want to use Aerogarden pods, you can use any hydroponic net cup instead. You will need to drill an appropriate size hole in the bin lid for the net cup you are using. Additionally, you will need to secure the drip feed tube from the pump to your net cup using a zip tie or other creative means. I am sure you can figure something out.I primarily use Aerogarden pods because (as you have probably guessed) I also have Aerogardens and it is convenient to be able to move plants from one system to the other. I commonly start plants in an Aerogarden and then once the seedling grows a long enough set of roots, I move it into this bin system.Check out my 3D printed Aerogarden pod design here: https://www.thingiverse.com/thing:4560879Check out my video about making DIY Aerogarden pods here: https://www.youtube.com/watch?v=LcrCVPn3DVE