The the following homemade hydroponics construction tips can help you
save money, build a safer system, avoid common problems, and increase
your chances of having excellent results. Some systems are more
difficult to work with than others so... keep in mind, hydroponic
gardening success begins with choosing a system design that fits your
requirements and your experience level. Before building a homemade system, consider the following things....
Before taking up your own homemade hydroponics construction project, you need to decide on the size of the system and how you will space the plants within the system. After my first year hydroponic gardening, I determined that small systems do not produce enough to make it worth the time and effort involved. The smallest system I would recommend would be 4'x 4' system, with a 4'x 8' system being more desirable in my opinion.
Of course, the size of hydroponic system you decide to build will be related to the size of light you have... a 4'x 4' system would be lit nicely by a stationary 600 watt light, while a 4'x 8' system would work well under two stationary 600 watt lights or one 1000 watt light on a light mover. Check out the light selector page for more information on lighting.
How you decide to space the holes in your homemade hydroponic system partly depends on what types of plants you choose to grow. Plants that are larger at maturity will require larger spacing. In my own systems, I place plant holes 10 inches apart (center to center). When I choose to grow larger crops, like tomatoes, I simply leave adjacent plant holes empty (but covered) to give every plant enough room for it's particular growth habit.
Whenever possible, try to use food grade plastics, or materials approved for carrying water in residential homes. For this reason, PVC pipe stands out as one choice. Recently I saw a homemade hydroponic system made from square PVC fence posts that worked very well.
Shops that specialize in beer and wine making equipment also have a selection of fermenters and food grade plastic containers that would work great for a homemade hydroponics construction project. A 30 gallon wine fermenter, for example, would make a good nutrient reservoir. Food grade plastics can be identified by a particular mark- the recycle symbol around the number 2- usually found on the bottom of the piece.
In the past, I have used cheap plastic storage totes as nutrient reservoirs and homemade hydroponic system parts. While I have never had any problems or suffered any ill effects from such use, over the years I have become more and more concerned about the possibility of unhealthy substances leaching from the soft plastics into the nutrient solution. Please be aware of this possibility before you decide to use them yourself!
As far as hydroponic pumps go, there are basically two kinds- low pressure pumps and high pressure pumps. Low pressure pumps develop about 2-10 psi, can typically lift water only two or three feet high, and can pump anywhere from 50 GPH to 700 GPH. Low pressure pumps cost less and also tend to cause fewer problems with leaking. Low pressure pumps are used in NFT systems, flood and drain systems, and sometimes in DWC systems (which technically require no hydro pump). For an average sized homemade hydroponics construction project (4'x 4' to 4'x 8') I recommend pumps rated at 240-380 GPH.
For high pressure pumps, psi is usually more important than GPH. High pressure pumps used for hydroponics typically produce 40-60 psi. High pressure pumps cost more and increase the probability of a leak at some point. High pressure pumps are used in drip systems and spray systems, including aeroponics. The high pressure is used to push nutrient solution through the tiny holes found on drip emitters and spray heads, which in turn control the flow rate (GPH).
In order to use highly pressurized water effectively, these systems require the use of a manifold. I also highly recommend using a filter AND a pre-filter inline before your water pump.
A manifold is a particular way to configure the pipes carrying pressurized water in a high pressure system, and are only necessary in high pressure systems. The reason for the special configuration is to ensure that every drip/spray head in the hydroponic system gets a steady supply of water at full pressure.
Consider a homemade hydroponics construction project with 36 plant holes and 36 spray heads. Each spray head needs at least 40 psi to spray properly. Through trial and error, you realize only 5 spray heads can be fed by a 1/2 inch line before it's pressure drops below 40 psi. At that point, you need a larger volume of water pushing into the 1/2 inch line to maintain 40 psi. In other words if you pressurize one long 1/2 inch line and weave it back and forth through your system, connecting each spray head one after another, only the first 5 spray heads are going to work when you turn the pump on.
Instead, a manifold starts by pumping water into a section of larger line (1 1/2 to 2 inch diameter pipe is typical) a couple of feet long. There are 8 sections of 1/2 inch line branching off of this first pipe. Some of the 1/2 inch lines feed 4 spray heads, others feed 5 spray heads. In this way each 1/2 inch line is backed up by a larger volume of water (the 2 inch line) and every spray head receives a minimum of 40 psi (because there are no more than 5 spray heads per 1/2 inch line).
Drip heads and spray emitters, both notorious for clogging, are components of high pressure systems. Incorporate drip heads/spray nozzles into your homemade hydroponics construction design only if you are comfortable working with high pressure, are prepared to pay for a high pressure pump (which can be expensive), and are prepared to give your hydroponic system the extra attention and maintenance it will require to work well.
To prevent algae growth your nutrient reservoir should be a dark color or opaque (to exclude light) and should have a lid. This is important because algae will attract fungus gnats, and fungus gnats will cause root damage to your plants. The reservoir should be large enough to hold all of the nutrient solution in your system in addition to the nutrient solution in the reservoir itself. Depending on the exact design of your homemade hydroponics construction project, this could prevent a flood if the power were to go out. Finally, the reservoir should be made of food grade plastic or otherwise be approved to carry water for human consumption (such as PVC for home plumbing).
The best way to save money on the expense of maintaining and reusing a hydroponic system is to use a re-usable grow medium. Take rockwool for example... replacing the grow medium every time you finish one crop and start another can cost you $100.00 or more, even in a small hydroponic system. The same is true for coconut coir.
Expanded clay pellets, lava rocks, or standing water (as in a DWC system) are the best options when it comes to reusable medium. This is done by securing the plants in netted pots in the hydroponic system. In between crops, the grow medium will have to be cleaned of any roots and soaked to remove the old nutrient solution. Another option is to grow your plants' roots in the air (aeroponics). Be warned, however, that aeroponics can be a temperamental and high maintenance system!