General Hydroponics

The following is from an article by Larry Brooks, published in Growing Edge, Fall, 1990. This comment is particularly relevant:

The plants are supported above the flowing nutrient. The roots hang down through an air gap in which nutrient is sprayed, then into the moving nutrient solution below the air gap. The nutrient sprayed through the air gap is not so much intended to feed the plant, but rather to infuse oxygen into the nutrient solution wherein the feeder roots remain constantly submerged. It is these submerged roots in oxygen rich nutrient that provides most of the nutrition and oxygen for the plant.

The Seattle Hydroponics aero-drip system is similar, but instead of spraying the roots, water is supplied to the top of the medium. I recommend grow-rocks for the medium, because it drains fast. I don't recommend emitters because they constrict the opening, which tends to lead to clogs. The higher flow-rate means you want a fast-draining medium like grow-rocks. Rockwool doesn't drain fast enough for this system, and is not re-usable (grow-rocks can easily be re-used).

Larry's system requires spraying the roots, and the sprayer tends to clog, isn't easily visible or easy to work on. The sprayed water doesn't penetrate the medium very well, so the plant basket has to be very small. Larry's system relies upon long roots growing into the nutrient solution, however to get roots this long may take a while.

My system enables a larger plant basket, so there is plenty of root space. This means your plant won't fall over. The water is passively irrigated by a large surface area (each bucket stores some water) and water trickling through the air.

The aero-hydroponic method was developed in Israel in the early 1980s. Dr. Hillel Soffer, senior researcher at the Volcani Institute at Ein Gedi developed the aero-hydroponic method to overcome the challenges presented by the hot, arid conditions at Ein Gedi. The discoveries that followed the development of aero-hydroponics offer great benefits to all hydroponic growers.

During a two-year period from 1986 to 1988, Dr. Soffer performed extensive research using the aero-hydroponic method at the University of California at Davis, where he had received his Ph.D. in the early 1970s. The specific area of research was in quantifying the effect of various levels of dissolved oxygen on root growth, especially in the propagation of plants from cuttings.

The findings of his research were published in the Journal of the American Society for Horticultural Science, and HortScience. Both studies were co-authored with David Burger at UCD. In addition, Dr. Soffer presented his findings at the annual conference of the Hydroponic Society of America in 1988.

Except for the papers mentioned above, very little has been printed up to now on the aero-hydroponic method. The method was patented internationally, though few licenses for the production of equipment have been granted. Without aggressive commercial support, the aero-hydroponic method has remained largely a research tool, known mostly to university researchers.In the meantime, the rockwool method was becoming available internationally following 12 years of exhaustive research and a strong marketing program with lots of investment in advertising, production and distribution, first in Europe and later in Japan.

Following nearly a decade of rockwool use, the Dutch contacted Dr. Soffer to request permission to develop and use the aero-hydroponic method. The reason for the sudden interest of the Dutch in the aero-hydroponic method has implications for the development of hydroponic cultivation worldwide.

For rockwool cultivation to work efficiently in most commercial operations it is preferred to a use a non-recirculating nutrient solution. Nutrient solution is sent on a one-way trip through the rockwool and is then discarded. The real cost advantage of rockwool cultivation over other hydroponic methods was that the nutrient did not have to be recaptured and recirculated, reducing the system complexity of reservoirs, plumbing, pumps and pH and conductivity controllers.

The once-through nutrient system also reduces the problem of nutrient solution becoming imbalanced due to erratic uptake of minerals by rapidly growing plants; plus the build up of dissolved minerals from slowly dissolving rockwool.

The discharge of enormous amounts of spent nutrient solution has become a major problem in Holland, contaminating surface and ground waters. Consequently, the Dutch government has prohibited the dumping of nutrients resulting in renewed interest in recirculating systems such as aero-hydroponics.

As leaders in both horticulture and commercial hydroponics, the Dutch have recognized the value of a method, which enables rapid and trouble-free cultivation and eliminates the problems of disposing of spent nutrients and exhausted media.

Aero-hydroponics is not a simple method to understand. The equipment required is somewhat more complicated than other hydroponic methods, but there is a great advantage in that once an aero-hydroponic system is set up, it will run almost indefinitely without additional investment in such disposable components as growing media and non-recirculating nutrients.

What is most surprising about aero-hydroponics is not how it works, but why plants grow better. The key is dissolved oxygen at the root boundary zone.

The essence of Dr. Soffer's work at UCD was in quantifying root growth in proportion to dissolved oxygen. Only the green parts of the plant can form oxygen from carbon dioxide - roots require a supply of oxygen for metabolism and growth. Plant growth in oxygen deficient conditions, such as those found in many soils, is limited. Dr. Soffer found the enhanced oxygen at the root zone produced enhanced growth.

In aero-hydroponics, the nutrient solution is sprayed through the air in order to infuse the nutrient with dissolved oxygen. The method differs from classic aeroponics in that most of the plant's roots are not suspended in air and fed by a spray of nutrient solution; rather, the majority of the roots are submerged in oxygen-infused nutrient which is in constant motion in order t maintain high levels of dissolved oxygen at the root boundary zone where oxygen and nutrients are taken in by the plant.

The result is a propagating tool of unsurpassed performance. Dr. Soffer was successful in propagating plant varieties at UCD that had never been propagated before. He took particular delight in propagating varieties of conifers and even pistachio trees (pistachio cuttings required 90 days to generate roots). Moreover, he found that cuttings could be rooted aero-hydroponically in purified water without using rooting hormones such as IBA or NAA. This is because plant tissue already contains the natural rooting hormone IAA (Indole Acetic Acid).

Aero-hydroponic systems can be built using quite a variety of materials and in numerous design configurations. The Ein Gedi "Mini Unit" which was used at UCD for dissolved oxygen studies is a stand-alone module which supports four plants in 10 liters of nutrient solution. An electric motor mounted on the top of the unit spins a nutrient sprayer, which lifts nutrient solution and sprays it onto the "aerial roots". Additionally, the rotation causes the nutrient within the unit to stir, moving it constantly over the submerged roots.

Large-scale aero-hydroponic systems follow the design of the commercial installation at Ein Gedi. These commercial systems consist of "canals" or growing chambers with plant sites on top. A pump provides the pressure to drive a system of sprayers to supply the aerial roots, while the submerged roots hang into the flowing nutrient in the canal.

Both of these systems share fundamental characteristics, which define the aero-hydroponic method. The plants are supported above the flowing nutrient. The roots hang down through an air gap in which nutrient is sprayed, then into the moving nutrient solution below the air gap.

The nutrient sprayed through the air gap is not so much intended to feed the plant, but rather to infuse oxygen into the nutrient solution wherein the feeder roots remain constantly submerged. It is these submerged roots in oxygen rich nutrient that provides most of the nutrition and oxygen for the plant.

Greetings,

I am writing to make you aware of a serious situation that has become a more widespread problem. If you don't use supplemental HID lighting, then this posting won't apply to your application. This email is for those people using electronic ballasts with HID (high intensity discharge) lamps. Electronic ballasts are being sold around the world at this time, and have been for several years, to the horticultural industry that are replacing traditional magnetic, "core and coil" ballasts.

What's the problem?

Your wall voltage, and the traditional ballasts, operate at a frequency of 50 or 60 hertz, depending on where you are in the world. Electronic ballasts operate at a higher frequency that can range from 22,000 hertz all the way up to 130,000 hertz +. Every HID lamp made, except one, was made for 50 or 60 hz Every major brand HID lamp on the market around the world will fail prematurely, or not ignite, on a high frequency electronic ballast. These failures have been happening for at least four years. Every HID lamp contains Mercury, among other gases, that are contained in the arc tube. By operating a 22,000 hertz ballast and using a 50/60 hertz HID bulb, you will have premature lamp failure. The ballast drives the lamp, like an amp drives a speaker. Imagine using a 60 hertz amplifier on a 22,000 hertz speaker, it's not going to last long because they weren't made for each other. A high pressure sodium (HPS) lamp for example, when used on an e-ballast, will cause the arc stream in the arc tube to rub up against the arc tube itself. That causes holes and fissures to form, and glues become unseated in the lamp, releasing the gases, including mercury. HPS lamps are typically never sealed at the mogul base, e.g. Hot runs to cold, a law of thermodynamics. Those hot gases in the lamp will then run out of the lamp through the holes in the lamp base. Whatever is underneath that HPS lamp will then receive the fallout from the gas, and mercury release. In our case, its the plants.

Who says that's true?

Hortilux, a very popular horticultural lamp manufacturer, says its true. In an article released in the October 2008 Maximum Yield magazine, written by Hortilux themselves, they stated their lamps were not suitable for use on electronic ballasts. There have been articles written about this topic in Urban Garden Magazine as well. This isn't new news, but it may be the first you're hearing about it, like most I speak with. The articles have been out some time now.

Just one brand of HID lamps, Sun Pulse Lamps, were designed for the high frequency electronic ballasts, a simple statement of fact, not sales. These lamps have been out for almost a decade, and have been proven in the field. All other HID lamps weren't designed for the electronic ballast. You can call the lamp manufacturers yourselves, and ask, "are your HID lamps certified for use on high frequency electronic ballasts?" They'll tell you they aren't. Sun Pulse was the only company that could say yes, and explain why.

If you look into this independently, you'll discover the same thing that I have, that there are an epidemic of lamp failures happening now, and this must be stopped. Any savings you might get by using an electronic ballast, is lost when the wrong lamp is used. The problem here is that the lamp companies don't make ballasts, the ballast companies don't make lamps, and they don't integrate together. It needs to be a certified matched set.

This email is to insure the safety of the end-users, who didn't hear this message when buying these lighting systems with electronic ballasts, and also to insure the safety of our food supply.

Dan Lubkeman, President

Hydroponic Society of America

Hydroponic gardening is available today with the latest advancements in hydroponic and lighting technology developed at Seattle Hydroponics. We also offer organic plant fertilizer, and pure chemical plant food--in such brands as NuFarm, General Hydroponics, Advanced Nutrients, House and Garden, Botanicare, Budswell, and Earth Juice. A hydroponic system with horticultural lighting, or organic soil with agricultural plant lighting, both can yield good results. Coco-peat is another good option, about halfway between soil and hydroponics. Hydro-tech is a full-service grow shop, offering discount hydroponics for hydro-gardening, in addition to growlamps and General Hydroponics fertilizers.

Hydroponic Light energy for plant growth can be provided by a wide variety of grow lamps: standard metal halide, high pressure sodium, ceramic metal halide, or pulse-start metal halide. Lighting is the most important element in plant growth. Ceramic Metal Halide is the best single light for growing plants; because it is full-spectrum with a balance between red and blue spectrum. The GE Digital Maximum is the only electronic ballast capable of runing the Ceramic Metal Halide bulb, because low-frequency output is required. CMH bulbs can also be run on the HPS magnetic ballast, typically 400 watt. The Pulse-Start Metal Halide bulbs can come in different spectrums: cutting/rooting: 4K rapid vegetative: 6.5K last week of veg: 4K most of bloom: 3K last week of bloom: 10K

Either switch all PSMH bulbs for each stage, or use a combination and blend together for full spectrum with a spinner. Super HPS (premium hps like Eye Lighting Hortilux) or standard high pressure sodium have been used for indoor gardening. pioneered in Seattle. However the HPS is an incomplete spectrum, and would need to be supplemented by blue spectrum light. Hortilux is a super-sodium, the high output partially compensating for the deficiency in blue spectrum. Putting a halide bulb together with an HPS bulb in the same outer jacket is not a good way to achieve full spectrum; because the halide lasts only half as long as the HPS, bulb life is shortened. CMH has more blue than a conventional Metal Halide, and more red than the HPS (which is mostly yellow-orange). Using the same ballast for both MH and HPS arc tubes causes inefficiency, whether swtiched or in the same outer envelope.

The Digital Maximum ballast is made by General Electric (GE). The Digi-Max light is the Digital Maximum with Life Light Technology socket fixture and reflector.

The Digital Maximum Digital Ballast has a microprocessor for better bulb performance; and will run CMH or PMSH bulbs by General Electric, Venture or Philips. For 600 Watt and 400 Watt E-Ballasts we feature the Lumatek Ballast. The Lumatek e-ballast will run Pulse-Start Metal Halide (PSMH), or Probe-Start Metal Halide (Old Style MH), or High Pressure Sodium (HPS); but not Ceramic Metal Halide (CMH). Which is why we carry Lumatek e-ballsts for 600w and 1000w, but the GE Digital Maximum e-ballast for 250-400 watt range, as well as the 100w CMH sidelights

The future in hydroponic gardening is available today with the latest advancements in hydroponic and lighting technology developed at Seattle Hydroponics. We also offer organic plant fertilizer, and pure chemical plant food--in such brands as NuFarm, General Hydroponics, Advanced Nutrients, House and Garden, Botanicare, Budswell, and Earth Juice. A hydroponic system with horticultural lighting, or organic soil with agricultural plant lighting, both can yield good results. Coco-peat is another good option, about halfway between soil and hydroponics.

Hydro-tech is a full-service grow shop, offering discount hydroponics for hydro-gardening, in addition to growlamps and General Hydroponics fertilizers. Light energy for plant growth can be provided by a wide variety of grow lamps: standard metal halide, high pressure sodium, ceramic metal halide, or pulse-start metal halide.

Lighting is the most important element in plant growth. Ceramic Metal Halide is the best single light for growing plants; because it is full-spectrum with a balance between red and blue spectrum. The GE Ultra-Max is the only electronic ballast capable of runing the Ceramic Metal Halide bulb, because low-frequency output is required. CMH bulbs can also be run on the HPS magnetic ballast, typically 400 watt. The Pulse-Start Metal Halide bulbs can come in different spectrums:

cutting/rooting: 4K rapid vegetative: 6.5K last week of veg: 4K most of bloom: 3K last week of bloom: 10K\par

Either switch all PSMH bulbs for each stage, or use a combination and blend together for full spectrum with a spinner. Super HPS (premium hps like Eye Lighting Hortilux) or standard high pressure sodium have been used for indoor gardening. pioneered in Seattle. However the HPS is an incomplete spectrum, and would need to be supplemented by blue spectrum light. Hortilux is a super-sodium, the high output partially compensating for the deficiency in blue spectrum. Putting a halide bulb together with an HPS bulb in the same outer jacket is not a good way to achieve full spectrum; because the halide lasts only half as long as the HPS, bulb life is shortened. CMH has more blue than a conventional Metal Halide, and more red than the HPS (which is mostly yellow-orange). Using the same ballast for both MH and HPS arc tubes causes inefficiency, whether swtiched or in the same outer envelope.

The Ultra-Max ballast is made by General Electric (GE). The Digi-Max light is the Ultra-Max with Life Light Technology socket fixture and reflector. The Ultra-Max Digital Ballast has a microprocessor for better bulb performance; and will run CMH or PMSH bulbs by General Electric, Venture or Philips. For 600 Watt and 400 Watt E-Ballasts we feature the Lumatek Ballast.

The Lumatek e-ballast will run Pulse-Start Metal Halide (PSMH), \line or Probe-Start Metal Halide (Old Style MH), or High Pressure Sodium (HPS); but not Ceramic Metal Halide (CMH). Which is why we carry\line Lumatek e-ballsts for 600w and 1000w, but the GE Ultra-Max e-ballast for 250-400 watt range, as well as the 100w CMH sidelights.