Ebb and Flow Hydroponic Systems
An ebb and flow hydroponic system (also called a reservoir system) is one of the easiest to build and maintain. The simplicity and low cost setup make it an ideal garden choice for the home hobby gardener. The basic setup is a growing tray containing plants in containers, usually filled with a growing medium such as clay pebbles, rockwool, or perlite. The growing tray is suspended above a reservoir filled with water and hydroponic nutrient solution. Water is pumped from the reservoir to the growing tray on a timed schedule, then drains slowly back into the reservoir. This draining action provides a steady flow oxygen to the plant's roots. To keep the system running smoothly, an overflow drain is usually installed to regulate the maximum water height.
Building an Ebb and Flow Hydroponic System
You will need the following parts to build your own ebb and flow hydroponic system:
To protect your roots, use a tray that does not permit any light to shine through. Plastic is usually a better choice than wood or metal due to its lighter weight and durability. Check your tray thoroughly before use to ensure that the water will drain completely back into the reservoir. Pools of standing water can lead to root rot, pest problems, and/or mold.
Any non-metallic plant pot with drainage holes will work with an ebb and flow system.
Almost any growing medium can be used with this type of hydroponic system. Clay pebbles (sometimes called grow rocks) can be very effective, even when not mixed with another medium. Due to the frequent flooding cycles, you don't want your growing medium to retain a lot of water.
You will need something to suspend the tray above your reservoir. Whether you choose to use a table, milk crate, or a custom-made solution depends on the size and configuration of your indoor garden. All you need is something sturdy that will hold the full weight of your plants and water. Don't underestimate the weight of water when planning your hydroponic garden design. Also, remember to plan ahead for the full size of your plants. It will be nearly impossible to switch to stronger supports once the tray is full of growing plants.
Any large plastic container will work as a reservoir (Rubbermaid tubs and trash cans work very well). Metal is not a good choice because it will rust over time.
Your garden will need two drains: one to drain the water back down to the reservoir and the other to serve as the overflow drain. The fill pipe usually also serves as the drain pipe, allowing the water to go back down the same route it came up. The overflow pipe should be placed at the desired maximum water level for your garden system. Make sure the overflow pipe can handle the amount of water your pump will put out or you will flood your grow space. Your goal should be to pump through about 125% - 135% of the amount of water your tray can hold. This will ensure a complete flow of nutrients through the growing medium and avoid salt and mineral buildup.
The size of your pump will depend on the size of your hydroponic system's needs. Pumping more water or increasing the distance it must travel will require a stronger pump. An aquarium pump will suffice for most small-scale setups.
The cost of your timer also depends on your indoor garden's specific needs. Most hobbyists running a single time schedule will be fine with a cheap timer from a Home Depot or Lowe's type store. Large-scale ebb and flow systems may require more than one timer or a more sophisticated timer that allows you to control more than one section at a time.
Flexible Plastic Tubing
Any flexible tubing will work, just make sure it is not transparent to avoid possible algae buildup.
Care of an Ebb and Flow Hydroponic System
Once you have your system and timer set up, your indoor garden should essentially maintain itself. Keep an eye out for any problems, especially flooding, pooling water, or algae. Unless you have a battery backup, you may have to reset your timer in the event of a power outage. Check the nutrient concentration and pH level of your nutrient solution regularly. Use a lower strength concentration of nutrients when adding to the water already in the reservoir.