for the do-it-yourselfer worried about leaks
The first thing any of us are faced with when building our own hydro system is the plumbing. Distributing the solution from the pump, and in some cases (such as that shown here) returning solution to the reservoir when the reservoir is not directly under the growing bed, are points we have to consider.
Any experienced do-it-yourselfer knows the importance of having a well stocked assortment of materials to choose from when building anything, especially a prototype. Building ones first hydro system qualifies as a prototype in my book. Having a convenient choice of accessories allows one to find the right part for the job instead of having to settle for second best, or making countless trips to the home center or hardware store. So I recommend not scrimping when you gather small parts such as fittings, connectors, etc.. I'm also a strong believer in the modular concept, and prefer using "off the shelf" products over reinventing the wheel.
As far as hydro plumbing is concerned I like to use materials that allow me to easily change, move, replace, or add any of them at any time. I stay away from anything that requires gluing or otherwise would be considered a "permanent" installation. This allows one to add to their system or modify it without major headaches.
Three kinds of tubing are used here, 1/2" to handle overflows and return solution to the reservoir, and 1/4" for feeding & siphon draining, all readily found at any garden center. It's a good idea to always have a supply of each on hand.
The 1/2" and 1/4" poly tubing is commonly found with low volume watering supplies, usually for fixed outdoor underground installations and/or drip irrigation systems. Some common brand names are Moisture Master and Nelson Rainscapes. Any 1/2" plastic garden hose fittings will work with both types of 1/2" tubing, but there are special fittings (elbows, tees, etc) made just for the 1/2" poly tubing, they are also readily available where low volume watering supplies are found.
Where one finds the poly tubing he will also find fittings to be used with it. Make sure you get the tool for punching holes in the 1/2" poly tubing. One of the best aids I've come across is a package of assorted fittings sold under the Gardena brand name (model #6203). It contains tees, elbows, caps, end plugs, hole plugs, and end caps for 3/16"ID and 1/2" tubing. Other manufactures also offer various fittings of these types.
One little known advantage of the 1/4" flared connector fittings (normally used to tap into 1/2" poly distribution lines, or to connect two loose ends of 1/4" tubing together) is that they can be used as a snap-in fitting with "any" soft resilient plastic that you can punch a hole in. This includes Rubbermaid containers and vinyl planter boxes. Notice the feed/siphon fitting in the illustration to the right, the fitting projects inside the bucket about the same distance it projects from the outside in the illustration. When the hole size is right it will snap-in and self seal, this provides a very good anchor for a tube, so good that the fitting has to be cut to be removed. I use this technique to anchor 1/4" feed lines to the bucket or planter box instead of running the tubing over the top then taping or clamping the tubing. It's much more secure and cannot be accidentally moved or dislodged when anchored in this fashion.
When one brings home a pump the first chore at hand is how to adapt it to the purposes at hand. Simply feeding water to the trays is not the only purpose, one must also empty and refill the reservoir routinely, so the manifold will also be used to accept a garden hose for those purposes. Since the manifold is immersed in nutrient solution all the time you must use non-corrosive materials such as plastic or stainless steel.
The outlets of pumps vary in size, so the first thing to do is to decide what is needed to get the 1/2" vinyl tubing attached to the outlet of your pump in order to use it as a manifold.
If your pump has a garden hose thread discharge, use a garden hose fitting for 1/2" garden hose (make sure it has stainless steel screws). If it has a 1/4" MNPT discharge you may be able to simply slide the 1/2" tubing over the pump discharge and fasten it with a plastic or stainless steel clamp, or buy an adapter for 1/2" tubing (both are found at any good water pump or pond supply display). The pump here has a 1/4" MNPT so I'll describe that setup below, you can click the picture on the left for a visual description.
To a very short length of 1/2" tubing terminating with a suitable garden hose thread attach a garden hose "Y" adapter that has a shutoff valve on each of the two sides of the "Y". At least one side of the "Y" should also have a snap-on type of garden hose connector to match that on the garden hose you will use to fill and drain the reservoir. The other side of the "Y" will be used as the plants nutrient supply. With this "Y" and its valves you will easily be able to shut off the supply of solution to the trays while using the pump to drain the reservoir. Simply snap-on the hose, turn two valves, then turn on the pump to empty the reservoir. You can refill the reservoir straight through the pump just by connecting the other end of the garden hose to your water supply. For the tray supply side, take a length of 1/2" poly tubing, punch holes, and snap-in the connectors for as many 1/4" feed lines as you need. Use an end plug on one end, connect the other end to the vacant side of the "Y" adapter with a garden hose fitting. In the case here, an "L" shaped nutrient supply manifold is needed and uses a Tee connector with the 1/2" poly tubing to create an L shaped supply side manifold. For a detail of the manifold components click here.
Tips & Techniques
Use one unbroken 1/4" line to run from the manifold to each tray. Don't be cheap and use sections of left over tubing with joining connectors, you're asking for potential trouble spots if you do.
Any 1/4" tubing gets less flexible with use. The insides also tend to accumulate a coating over time. For these reasons you may consider replacing the 1/4" tubing every few crops or so.
If a tube loses some flexibility and wont hug a fitting as tightly as it otherwise could, use a one inch length of tubing with 1/4"ID to slide over the 1/4"OD tube, then slide it over both the small tube and the connector.
If hoses are difficult to get on the connectors, hold the hose in a cup of hot water first to soften it and make it more flexible. A little petroleum jelly can help too.
At the end of the 1/4" tubing leading to the bucket you can attach a small plastic tee. However, I strongly recommend you use the simple snap-on assembly (shown on the right) instead, and insert it as well as the 1/4" feed/siphon line to a snap-on fitting installed through the side of the bucket just below the overflow. Plastic tees, rigid plastic tubing, and elbows can be found at any aquarium store (or auto supply store under vacuum fittings), black 1/4" poly tubing is found at garden centers with the low volume watering accessories in the garden hose department (tubing must be black). The tubing can be used to tightly join the parts together.
Place the plastic tee at the lowest point in the bucket or planter box for complete drainage and anchor it to the side or lip of the container so it wont move from the surge of water when the pump turns on. Run it into the bucket at the same place the overflow is located. When solution squirts from the tee it should squirt to the left and right, not up or down. These buckets usually have a slight depression running around the outer wall of the bottom, this depression is ideal for the Tee and will act as a sump. The illustration above and to the right shows a short length of poly tubing being used to connect a Tee to a section of rigid plastic tubing, which is in turn connected to an elbow. The elbow snaps onto a 1/4" fitting anchored in the wall of the bucket. This simple assembly is used in all the trays because of its secure anchoring, though its function of feeding/siphoning can be accomplished by placing a Tee directly onto the end of the tubing run.
Gaining access to internal tray parts
Next you will need something to prevent the growing medium from resting against the tubing and overflow outlet. Any plastic cylindrical object sliced down the middle, then placed against the inside wall of the bucket will do. Even a short section of vinyl rain gutter will do as a fence of sorts. This allows you to remove the tube and Tee if needed, and prevents the medium from covering the orifices or making the feed/siphon fitting or line inaccessible during the time a plant is growing in the bucket. Since the solution flows in and out of the tee, a natural self cleaning effect is created. It will spit out roots before they have a chance to grow into the orifices, and because the solution siphons up when the bucket empties instead of draining down, there are no drain holes in the bottom of the bucket to leak or be clogged by gravity-driven roots.
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