hydroponic

Up to this point we have concerned ourselves with the plant, the system that feeds the plant, and the nutrient that the plant is fed. The plant and the system, however, do not exist in a vacuum. The environment that the system exists in is every bit as important as the medium in which the plant anchors its roots. The air temperature, humidity, flow, light, and several other environmental factors all contribute to the quality of life that effect your plants. Hydroponic gardeners simply do not set their gardens up on the kitchen table and watch their plants grow. While this is certainly an option, most will go the extra step to further provide the right conditions for their indoor gardens. That includes lighting, air control, and more. How sophisticated you wish to be is up to you.

Lights

If you are running a hydroponic system in an outdoor greenhouse, you may be able to rely on natural lighting for your plants. In any indoor case, you will have to provide lights. Unfortunately, this can be nearly as complicated as your water system itself because you need to provide light that is as close to sunlight as possible. Your average room lights will not be sufficient. Before any further discussion on lighting options, you need to know more about the properties of light.

Understanding light intensity

When it comes to measuring light, most people think of watts. A standard incandescent light bulb was between 60 and 100 watts before the advent of compact fluorescent bulbs. Now a “standard” bulb is about 23 watts when using CFLs. Many people use the term to describe how bright a light is even though that is not really what watts measure. Watts is a term used to measure energy or power.

True brightness or intensity can be measured with various units such as lumens and lux. Lumens, known in other terms as luminous flux, measure the perceived power of light from a natural or artificial light source. Simply put, lumens measure of how bright a light source is, not taking distance into account.

Lux is the measurement of the apparent intensity of light at a given distance. A light source ten feet away will have a far greater lux than if you were 100 feet away.

Nonetheless, most light bulbs are sold with wattage ratings rather than lumens or lux, so that is still likely the information you are going to have to work with when you are shopping for lights, though it is well worth your while to know the definitions of each of these terms and how they apply to your situation. As a point of comparison, a typical 23-watt household light bulb will put out approximately 1,500 lumens. A 125-watt bulb will produce 9500 lumens.

Understanding the color spectrum

Many people are familiar with wattage, but understanding the color in light is usually a new concept. It is a very important one though. Even very subtle color components can impact your plants.

Lights that lean to the red end of the spectrum will promote flowering and fruiting, and lights with more blue will encourage faster overall growth and leaf production. Sometimes these lights are known as warm and cool, respectively. Since you are in control of your lighting, you can make bulb choices that favor your growing needs. Herbs and leafy plants will do better with cool lights, and most other plants will produce better under warm. And sometimes, combinations of each type will work to your advantage as well.

Kinds of lighting options

Even something as simple as a light bulb is going to come in several varieties. There are actually many different kinds, and they all may or may not have a place in a hydroponic system.

Household incandescent bulbs are not very good for several reasons. They do not provide the proper spectrum of light, and they are extremely hot compared to fluorescent bulbs. In an enclosed area, heat is very important and will be a detriment to your gardening. Not to mention the short life span of an incandescent bulb. Considering your lights will be on for most of the day, every day, you will spend a lot of time replacing bulbs if you use incandescent bulbs.

Primarily, two kinds of lights are used in hydroponics, though lighting is currently going through a great deal of change. High pressure sodium and metal halide have been the lights of choice for gardeners in the recent past. Both are considered high intensity discharge (HID) lighting. While these are the better quality lights intended to be used as grow lights, small hydroponics setups can be very successful with regular room-lighting fluorescents as long as you get them large enough and bright enough for your plants. Here are the basic points about each type of lamp, without going into the chemistry that makes one different from the other.

High-pressure sodium (HPS) bulbs have more light in the red end of the spectrum, with metal halide (MH) bulbs leaning the other way to the blue end. Overall though, MH lights offer a wider spectrum of light and are closer to natural sunlight in terms of the color content. Large hydroponic operations often combine the two in order to create the most complete possible spectrum. Most home gardeners will not have the space or the budget to manage two different sets of lights, so you will have to make a choice. MH lights are the more practical choice for most indoor gardening situations but if you have a setup that does get a significant amount of natural sunlight already, then you can use HPS as a supplement.

Both types of bulbs are offered on the market in a range of wattages, running from 150-watt to more than 1000-watt. Costs are comparable, though MH lights can be more costly at the higher wattages. That also will depend on the manufacturer, as some are more expensive than others.

LED lights (light emitting diode) seem to be the wave of the future of lighting. LEDs last much longer than anything currently on the market and will give the gardener the ease and ability to offer plants the specific colors necessary for each stage of growth. LEDs allow the hydroponic gardener the ability to create custom wavelength combinations for their plants to adjust the photosynthesis and/or photomorphogenesis responses of the intended plant. With LED lighting, the hydroponic gardener can tailor the lighting to the ideal needs of specific plant species. By combining customized wavelength combinations with easily changed LED lights and light fixtures, the hydroponic gardener can change the photosynthesis and/or photomorphogenesis response of the specified plant, allowing more vigorous growth in shorter periods.

While LEDs are currently somewhat more expensive than other forms of lighting options, the hydroponic gardener will find that, in the long run, they are less expensive to maintain. The lights are also much cheaper to operate than anything currently on the market. Determining precisely what your cheapest lighting option is can be a bit of a complicated science, as you need to go beyond the cost of the lighting equipment and the cost of powering the lights. You also need to consider the results generated by the lights. At the end of the day, LEDs seem to lead the pack and are well worth your further exploration.

The use of LEDs for growth operations is a brand new field at the time of this writing, but it is well worth any indoor gardener’s time and effort to stay current on this topic. LEDs have been available to the home gardener for only about three to four years.

Ballasts

The above section has dealt with bulbs and the components of lighting that actually produce light, but lighting has more to it than that. Fluorescent bulbs (either HPS or MH), incandescent lights, and LEDs all will require the proper sockets and fittings in order to use them. They are called ballasts, and the ballasts needed for each kind of light source varies with the lighting option you choose.

Ballasts contain capacitors and transformers to manage the power coming into your lights, and they also are designed to dissipate the heat build-up that comes with running lights. They are rated for different wattages, so you need to plan your purchase based on the lights you plan to use. If you are just starting out, you should get a complete lighting kit that includes all the bulbs, sockets, ballasts, and even a reflector all in one purchase, so that you know everything works properly together.

The ballast is housed in a small box, which either can be installed directly to the light bulb or left on a nearby flat surface and attached to the light with the appropriate cord. Each ballast usually has an on/off switch and can be controlled by a separate timer if you are going to have your lights operate automatically.

Light placement

Now comes the more important information about how to determine how many lights you need and how you should arrange them for maximum efficiency. The following information is related to the use of incandescent lighting. The use of LEDs requires much less energy.

A very rough estimate of lighting needs is 40 to 75 watts per square foot of growing area. So a 1200-watt light fixture could supply light for at least 30 square feet of plant space. This is a place to start with your calculations, but it is not the final figure. How high you hang your lights also will come into play. Your lights will have to be adjustable so you can raise them up as your plants grow. Chains are the best option for this since you can hang your lights on hooks, and then just change which links are used to move the light up or down.

Having the precise position of your lights for optimum growth is a nice idea, but it is not an easy one to achieve for the novice. This is where you need to do some work figuring out lumens and lux based on the wattage of your lights. You also should have a good light meter on hand to help you measure the light accurately, so you are not guessing about intensity or distance.

Reflectors

The lights themselves are only part of the system. To make your lighting arrangement as efficient as possible, you want to have a little more control over how the light is cast over your plants. The main way to do this is with a reflector.

Though there are different varieties and styles on the market, all reflectors are basically the same concept. A reflective hood is attached over the light bulb so that light is not wasted by shining it upward, away from the plants. Light is reflected down where the plants are. Using a reflector will bring more light to your plants, more so than what the initial wattage rating would indicate. So if you are going to install reflectors over your lights, you should use a light meter at plant-level to see precisely how much light is going to be used by your plants.

LEDs, generally, do not require reflectors, as the lights are precisely directional to begin with. One of the strengths of LED lighting is that there is not much spillage, and very little light is wasted in dispersal.

Light movers

Reflectors are probably obvious and are a very logical addition to your light fixtures. But you can add another level of control by using movers. These are not strictly necessary and most beginners will not want to use them due to their cost.

A light mover is a powered track that allows your light fixtures to move, usually from one side of the room to the other. The purpose is to mimic the natural movement that would happen with sunlight and to allow more of your plants to get the full effect from each light. If you were to have one single fixture over your plants, you would be able to provide its full effect across the entire growing table if the light shifted positions through the day. It may be a reasonable alternative to buying a second light and ballast.

Temperature

After lighting, you will want to turn your attention to the temperature of your growing area. You need to keep the area warm enough for your plants to thrive but prevent it from overheating (which can happen due to the lights and other constantly running power equipment).

There is no optimum temperature that will suit all plants, so you will have to choose a comfortable range for everything you are growing. Most plants will be happy at 75 degrees F during the day with a drop to 60 degrees F at night. A cooling period at night is necessary, so do not plan on keeping a static heat level 24 hours a day. If you are growing plants that are only going to thrive in cool weather (lettuce is a good example), then try to keep it cooler by around 10 degrees.

If your ambient home temperature does not suit this, you will have to add heat to your grow room. Seventy-five degrees is a little warm for most people. Before you start buying room heaters, see how much added heat the lights give off. Your grow room might maintain the proper temperature naturally after all. If you have a large setup, your lights may produce more heat than you want, even with active fans and exhaust venting. In that case, you may have to get a small room air conditioner to keep the overall temperature in the right zone.

CO2 Gas Supplementation

This is going to be a more advanced concept and not something for the novice to be concerned about at the start. Plants are living things that require oxygen (O2) to survive just as we do, but they also need carbon dioxide (CO2) to run their photosynthesis. They naturally produce CO2 on their own, but you can give them a boost by adding extra to their atmosphere.

Typical room atmosphere will have about 300 ppm (parts per million) CO2. Plants will start to show the most benefit from it when the levels reach at least 1000 ppm. You definitely will need to get a meter to measure the levels, so you do not over-gas your plants. We will learn more on carbon dioxide meters in the next section of this chapter.

Commercial operations routinely use additional CO2, and they report that it can boost overall productivity by up to 20 percent. Whether that justifies the additional effort and equipment costs is up to you. It also will require that you have an enclosed area for your setup to keep the gas contained.

There are two common methods for adding carbon dioxide to the environment. The first is the use of bottled pressurized gas. Using a control valve on the bottle and air hoses to deliver the gas to your plants, you can boost the overall CO2 levels. These types of gas bottles are large, heavy and get expensive to have refilled, so this is not an ideal option. It may be a decent approach to first try the technique and see if your plants benefit. If it is something you want to consider, then you can take it a step further with a proper CO2 generator.

These generators produce carbon dioxide by burning natural gas or propane, by means of a burner and pilot light. Green Air Products makes some popular models of carbon dioxide generators that work well in hydroponics, and they will cost a few hundred dollars each.

They also produce heat, which may be a positive or negative for your system. If you already need a little extra heat for your plants, this would be a good way to do that without adding a heater as well. Otherwise, you will need to watch the temperature carefully and allow for fans and venting to release the added heat. Since heat rises and CO2 falls, a vent that is higher on the walls or the roof will help let out the heat without letting out the CO2 you are trying to accumulate.

Carbon dioxide enrichment will only help your plants while the lights are running and the plants are actively photosynthesizing. Whatever method you are using to produce CO2 can be shut off at night without any detrimental effect on your plants.

When using any type of CO2 enrichment, you will need to have a fan or two in place as well to keep the gas moving in the area. Carbon dioxide is heavier than oxygen, and it will sink if left on its own. Hoses that deliver gas directly to the plants will help overcome this if you are using bottled gas.

When you boost your plants’ metabolisms, you will find that they start to draw more heavily on other resources as well. Any previously adequate levels of water and nutrient likely will be insufficient once the carbon dioxide starts to take effect.

Also, keep in mind that CO2 will be toxic to you and your family if levels rise too high in the rest of your home. Take proper measures to keep your carbon dioxide additions limited to your grow area, and keep a good monitor (with alarm) to let you know if it starts to leak into the rest of your home.

Meters

With all these variables, you will need to plan to have some meters to measure your hydroponic environment. There are several that will come in handy when you are setting up your grow room.

Thermometers

This one, used to measure the temperature of your grow space, is fairly simple and straightforward. As mentioned in the temperature section above, you have to take care not to let your space overheat from all the lights. Any standard thermometer can help you keep track, though a digital one can be easier to read than the old-fashioned “mercury” style.

A thermostat can trigger fans and heaters to help maintain a steady temperature in your growing area.

Hygrometers

A hygrometer measures the humidity in the air. High humidity is an inevitable result of all the flowing water and liquid in hydroponics, which is usually quite fine as plants like having a lot of moisture around. Like with any factor, you can have too much of it. If there is too much moisture in the air, your plants will not be able to breathe properly or take in new liquid (and therefore nutrients) through their roots. You will want to aim for between 65 and 70 percent humidity for most plants, though flowers can do better with 55 to 60 percent.

Since adding humidity is rarely necessary, it has not yet been discussed as an atmospheric requirement. You can up the humidity in your grow room by adding some open buckets of wet sand. A proper humidifier also can work if you do not mind yet another piece of equipment running. If you do have excess moisture, you just have to run a dehumidifier or add additional venting to the room to remove the wet air. You also could look at your nutrient solution systems to see if you can reduce any unnecessary evaporation.

Carbon dioxide monitors

This is not as crucial as the other two unless you are adding additional CO2 gas to the grow area. There is more on this in the section previous to this one.

Do not confuse these with carbon monoxide (CO) monitors that are very common household items, often combined with smoke detectors. Carbon dioxide monitors are not as easy to find and will be more expensive, usually starting at around $100 apiece. Small chemical kits are cheaper if you are just periodically checking the air quality. Once you have established a steady and reliable system for adding CO2, you should not need to have a constant monitor running, but that choice is yours.

Power usage monitors

This is the only item on this list that will not actually have any impact on your growing success. It can have a serious impact on your monthly electric bill though. Lights, pumps, and fans all have a significant power draw to them that leads to one of the main negatives of hydroponic gardening: the cost of electricity. You will not be able to eliminate this issue altogether, but a good voltage meter can go a long way in keeping it under control.

These devices are fairly commonplace and can be purchased at most home renovation or hardware stores. They plug into a wall outlet, and then the device to be tested is plugged into the monitor. After a few moments of operating, the LCD screen will tell you exactly how much power is being drawn. Kill a Watt® is a good brand name, and Blue Planet™ also makes a nice monitor. You would not have one running all the time but you can use it to test the various pieces of equipment periodically to see if anything is drawing more power than you can afford.

You then can lower your overall usage by replacing some items or changing how you run your system.

Fans and Vents

With all these issues involving the air inside your grow space, it should be no surprise that maintain fans and vents will be necessary. Not only do you need to vent out unwanted stale air, you also need to bring in fresh air at the same time. That is, without letting out valuable humidity, heat, or carbon dioxide. It definitely can be more difficult to manage than just cracking a window open.

Not only will you need to move air in and out of the grow room, but you also have to move air around within the room as well. Heat rises and carbon dioxide falls, which will create layers of air through the room that will need to be mixed. Simple room fans are all you need to eliminate this, and those that oscillate work best.

Moving air in and out of the room will be a little more complicated. As mentioned earlier, vents to release hot humid air should be placed higher in the room because heat naturally rises. Add an intake vent lower down to provide a path for better air circulation through the room. All vents should be covered with mesh to keep out insects and other pests. Powered fans can be operated within the vents to keep the air moving if the natural flow of warm and cool air is not enough.

Timers

With so many variables under your control, you will be relying on several different types of timers to keep it all running smoothly. Nobody wants a garden that needs to be attended to every 30 minutes because something needs to be turned on or off. Timers are a vital part of most hydroponics setups.

For something as simple as a daily on/off switch, you can do fine with a standard household timer used to switch lights on and off in a house. The simplest ones have a large dial in the center that turns as time passes. You place small plastic pegs along the rim of the dial so that it triggers the on/off switch as the dial turns. If you have enough pegs, you can have several on and off cycles through the day.

These types of mechanical timers are fine for some lighting applications and some irrigation needs as well, but they will not allow for enough on/off cycles for most types of hydroponics because the water pumps go on and off so frequently and sometimes with time frames too small for the larger timers to manage. If you only need a mister to come on for 30 seconds at a time for example, you will need a more sophisticated timer.

Digital timers are not that much more expensive and can allow for smaller time increments, though most will not handle any time period smaller than one minute.

Another thing to consider with either of these is the voltage requirements of your devices. Inexpensive timers meant for typical household lamps or TVs are not equipped to handle the power that will be required to start up a large wattage fluorescent light bank. You may be able to get away with simple timers for your water pumps, but make sure you invest in good devices to manage your lighting needs. Even so, they are generally not that expensive.

A digital timer from BetterGrow Hydro® can handle most individual lights up to 1200 watts and will only cost around $20. It can be programmed for up to eight cycles a day with time increments as small as one minute. At the other end of the scale would be a $300 repeat cycle timer from Green Air Products. That model allows for much more precise control with cycle duration times of as little as five seconds, and you can run cycles every seven minutes through the day. Optional photo sensors can be added so that the timer only operates during the night or day.

Air Filters

Smaller operations may not need these, but if you are growing a large number of plants, then an air filter can help prevent pollen and other plant debris from accumulating in your growing space. Pollen and smells from the plants can permeate your home, though if your growing room is well-sealed this may not become a problem for you.

A good standard household air filtration unit with a carbon insert should be sufficient for most hobby-sized gardens to keep the air in your grow room clean. It will not only keep odors and dust from traveling to the rest of your house, but it also helps eliminate any spores from the air that might cause a threat to your plants.

If you really want to clean the air, you will want a filter that will also generate ozone or has a UV light for pathogen elimination. Many good units have both. Depending on the model, they are typically installed on your air-intake vent so that all air entering the grow room is cleaned immediately.

These types of air-cleaning units are excessive for a typical indoor hydroponic garden, but if you plan to expand your operation or get into commercial growing, then you should consider getting one.

Water Filters

Your source of water will determine whether you will need to filter your water before using it on your plants. Standard tap water will have chlorine and fluorine added, which is not a healthy additive for your garden. Since using bottled water is not feasible, you should consider having some sort of filter for your water supply. This is not strictly necessary and can be ignored if you do not want the added cost or complexity. You can install a basic one on your tap or under the sink for wherever you intend to get your water (if your grow room does not have its own water supply). Brita® or PUR® units would work well and can be found in most home improvement stores.

You also will need to consider treating your water if your water source has a high amount of dissolved minerals in it (i.e. hard water). Not only will the mineral content interfere with your management of nutrient solution due to the unknown compounds already in the water, but the minerals also will build up a crust on your hoses, fittings, valves, and pots. Technically, this calls for water softening rather than filtration to fix, and water softener systems are fairly common as household appliances. Chapter 3 covers water chemistry, and you can find out more about water hardness there.

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