Hydroponic Basics

What is Hydroponics?

A person is holding a container in the grass.

Hydroponics is the method of growing plants in a solution of water and nutrients with or without inert growing media such as sand, coco, perlite, and hydroton. These media are used for supporting the plant and to keep the nutrient solution close to the roots. Hydroponic nutrient solutions are typically aerated because the roots need oxygen for respiration and growth.

What is Aeroponics?

A diagram of the aeroponic system with water and plants.

A plant-cultivation technique in which the roots hang suspended in the air while nutrient solution is delivered to them in the form of a fine mist. Aeroponic systems utilize misters and sprayers that periodically spray the roots with aerated nutrient solution. This type of system is a little more difficult to operate but the rapid rates at which plants grow results in amazing yields.

Advantages

The biggest advantage with hydroponics is the increased growth rates so you get maximum yields in the shortest amount of time. With a properly set up system, your plants will mature faster and provide over 30% increased yields. Properly set up systems include maintaining control of light levels, pH, nutrient solution strength, levels of dissolved oxygen in water, ventilation, and pest control.
Plants grown hydroponically always have an unlimited supply of water and nutrients which allows the plants to focus most of their energy growing shoots, foliage, fruits, and flowers.
Plants can be grown hydroponically both indoors and outdoors
Any plant can be grown hydroponically!

If you are not growing hydroponically, don't worry, Blue Planet Nutrients works excellent in soil as well!

Water Quality
Water is the foundation of all hydroponic systems. It is very important to know the quality of the water being used because most water already contains various minerals which can effect the pH stability of your nutrient solution as well as the availability of the nutrients for absorption by plants.

How Important is Water Quality in Growing?

A white shower head sitting on top of a floor.

Water containing excessive calcium and magnesium (ie. "Hard-Water") can cause serious problems. If the dissolved salts in your water supply measure 200 ppm or more, we strongly recommend that you obtain a water analysis to determine calcium content. Excessive calcium is the main factor in determining if your water is hard. If an analysis of your water supply reveals that the calcium content of your water supply is greater than 70 ppm (mg/liter) you should consider purchasing a reverse osmosis water filtration system to filter your water.

Is Chlorinated Water a Problem?

The most common issue regarding tap water and hydroponics is chlorine. Many growers don't realize that chlorine is a micro-nutrient required by plants in extremely minimal quantities. Chlorine is highly volatile and will evaporate from tap water within a day or sooner if the water is aerated. Because plants are able to absorb it, they wind up taking in far too much from unfiltered tap water resulting in diminished growth due to poor root health. The micro-flora and micro-fauna living in the root zone are very important for healthy vigorous plants and high yields. Don't let chlorine kill the good guys!

Chloramines are chemical compounds of ammonia and chlorine that are also used as municipal water supply sanitizers. Chloramines do not evaporate from water the way chlorine does and many water filters which remove chlorine cannot remove chloramine. The effects of chloramine on your garden are even more detrimental than chlorine. If you are concerned your tap water may contain chloramines, have it tested. To avoid problems caused by these chemicals, consider an investment in a water filter or reverse osmosis machine and make sure it takes out both chlorine and chloramine. The improvement in plant health can be considerable which translates to a substantial increase in harvest quality and quantity.

Oxygen and Roots?

A chart showing the temperature of an oxygen tank.

Plant root systems need oxygen for aerobic respiration, an essential plant process which releases energy for root growth and the uptake of nutrients. In a deep water culture hydroponic system, it is absolutely crucial to have adequate oxygen levels because roots are submerged. For optimal growth it is recommended to have 1 liter per minute of air pumped into each gallon of nutrient solution. Therefore a 100 gallon reservoir would require a 100 LPM air pump for maximum oxygenation. In every other hydroponic application it is only required to oxygenate the solution enough to prevent it from becoming anaerobic, which means much less air is required. Generally if you have good movement in the solution and the majority of the surface of the solution is broken with bubbles, your plants will do fine. This can be achieved with a simple fish tank pump and air stones.

What About Water Temperature?

As the temperature of your nutrient solution increases, the less your nutrient solution holds dissolved oxygen. The oxygen content of a fully aerated solution at 10°C (50° F) is about 13 ppm, but once the solution warms up to 20° C (68° F) the oxygen content drops to 9 – 10 ppm. By the time the solution has reached 30° C (86° F), then oxygen content levels are only at 7 ppm. We recommended not exceeding 76° F in your nutrient solution (ideal temp is 24° C or 70° F) in order to keep oxygen dissolved and available for plant roots.

6 Types of Hydroponic Systems

Deep Water Culture

This is the simplest hydroponic system there is. It is the easiest to use and produces wonderful results. In a DWC system, you use a reservoir to hold a nutrient solution. The roots of your plants are suspended in that solution so they get a constant supply of water, oxygen, and nutrients. Air stones and an air pump are used to oxygenate the nutrient solution allowing the roots to respire and grow.

What You Need to Build a Water Culture System:

Container to hold the nutrient solution (reservoir)
Aquarium air pump
Air line/hose
Air stones (or soaker hose) to create the small bubbles
Baskets, pots, or cups to hold the plants
Some type of growing media

How a hydroponic Water Culture system operates is easy. The plant is actually suspended in baskets right above the nutrient solution in the reservoir. Usually by cutting through the lid covering the reservoir. The roots hang down from baskets the plants are in, and hang down directly into the nutrient solution where they are submerged. The roots remain submerged all the time 24/7. The roots don't suffocate because they get the air and oxygen they need from air bubbles rising through the nutrient solution, as well as from dissolved oxygen in the water itself.

The more air bubbles the better for water culture systems. The bubbles rising should make the water look like water boiling at a heavy rolling boil. The bubbles should be rising up through, and making direct contact with the roots as they rise to the top of the water to be most effective for the plants.

Flood and Drain (Ebb and Flow)

Ebb and Flow (Flood and Drain) systems are very popular with home hydroponic growers for many reasons. Besides how easy they are for anyone to build, you can use almost any materials you have laying around to build them with, so you don't need to spend much money to grow plants hydroponically. Also they can be built to fit in any available space you might have (both indoors or outdoors), and there is no limit to the different and imaginative ways to design them for that space. Along with being inexpensive and easy to build, plants grow very well in flood and drain systems. The flood and drain system works basically like it sounds, by simply flooding the plants root system with nutrient solution. Only periodically rather than continuously.

How a hydroponic flood and drain system operates quite simple. The main part of the flood and drain system holds the containers the plants are growing in. It can be just one plant, or many plants/containers in series. A timer turns on the pump, and water (nutrient solution) is pumped through tubing from the reservoir up into the main part of the system using a submersible fountain/pond pump. The nutrient solution continues to fill (flood) the system until it reaches the height of the preset overflow tube so that it soaks the plants roots. The overflow tube should be set to about 2 inches below the top of the growing media.

When the water filling/flooding the system reaches the overflow tube height, it drains back down to the reservoir where it recirculates back through the system again. The overflow tube sets the water level height in the flood and drain system, as well as makes sure the water (nutrient solution) doesn't spill out the top of the system while the pump is on. When the pump shuts off, the water siphons back down into the reservoir through the pump (draining the system).

What You Need to Build a Flood and Drain (Ebb and Flow) System:

A container for the plant's roots to grow in.
A container (reservoir) to hold the nutrient solution.
A submersible fountain/pond pump.
A light timer to turn the pump on and off.
Some tubing to run from the pump in the reservoir to the system to be flooded.
An overflow tube set to the height you want the water level.
Growing medium of some kind.