Frequently Asked Questions


What is Hydroponics?
What is pH?
What is PPM?
What is EC?
What is the difference between High Pressure Sodium and Metal Halide?
Should I use Sodium or Halide?
Why do people use Metal Halides for vegetative growth and High Pressure Sodium's for flowering?
What size light should I purchase?
Do I need a ballast?
Are HID lights efficient?
Can I interchange bulbs between systems?
Do these lights require any special wiring?
What kind of plants can be grown using hydroponics?
How often should I change my nutrient solution?
Can I transfer plants from soil to hydroponics?
Do plants grown using hydroponics taste better than plants grown in soil?
What is the difference between Aeroponics and Aero-Hydroponics?
Why does an ebb and flow tray system have two fittings?
How often do I need to water my plants in an ebb and flow system?
How long should I water the plants for in an ebb and flow system?
What CO2 system is right for me?
What is the difference between Miracle-Gro and other commercially available fertilizers and hydroponics nutrients?
What is the desired temperature range for the nutrient solution?
How much electricity will I save running a grow light 240 volt?
How do I tell if my seeds are viable?

What is Hydroponics?
Hydroponics is the method of growing plants using a soilless media which could include a wide variety of examples like: gravel, peat, vermiculite Perlite, old rubber tires, rockwool, and expanded clay aggregates. The minerals that the plant needs are dissolved into the water which is then watered directly to the plants. So, in short instead of the plants searching throughout the soil for their minerals they draw them directly from the water that they are being fed.

What is pH?
A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. We recommend that you keep your solution at about 6.5 because that is the point at which the nutrients are the most soluble.

What is PPM?
PPM is very easily defined as Parts Per Million and can be used as the measurement of a number of different things. More commonly in the hydroponics world, this measurement is used to measure the amount of Total Dissolved Solids in your nutrient solution or how much CO2 is in your atmosphere.

What is EC?
EC is a unit of measure to gauge the Electrical Conductivity of a solution. An EC meter applies an electrical voltage to the solution and reads the conductivity that is produced from the motion of mineral Ions.

What is the difference between High Pressure Sodium and Metal Halide?
The difference between these two types of HID (High Intensity Discharge) lights is the color spectrum that is emitted from each. The High Pressure Sodium bulb emits light that is concentrated in the red to yellow side of the spectrum and are weak in the blue-violet end. While the Metal Halide bulb emits light that is very balanced and contains all the energy peaks at wavelengths of the visible spectrum. Visually the Sodium bulbs will appear very yellow-orange and the Halide bulbs will appear more blue-white in color.

Should I use Sodium or Halide?
The Halide lights have a very balanced spectrum and are excellent for vegetative growth or leafy plants like lettuce and basil. The Halide lights produce between 65-115 lumens per watt which is a measure of the efficiency of the bulb, or how much light you are producing for the amount of electricity you are using. The Sodium lights produce light that is very bright and concentrated on the yellow to red side of the color spectrum. This color is not as balanced as the Halide but makes up for the lacking of a balanced spectrum in the amount of light given off by the bulb. The Sodium bulbs produce between 97 to 150 lumens per watt which is much higher than the Halide bulbs. The Sodium bulbs are superior in life expectancy and efficiency while the Halides a superior in spectral distribution so your decision will be based on what is more important to you.

Why do people use Metal Halides for vegetative growth and High Pressure Sodium's for flowering?
Many people switch between bulbs for different stages of growth for a couple of reasons. First of all, Sodium bulbs have been known to make some plants grow leggy and stretched out because of the yellow to red spectrum that they give off. Metal Halides tend to keep these plants tighter with less space between internodes. So some growers use the Metal Halide lights during vegetative growth to keep the structural growth of the plant nice and tight. But they switch to Sodium lights when the plants begin to flower because the Sodium lights produce so much more light than the Halides. Even though the Sodium's do not have as good a spectrum as the Halides the intense light that is put off by the Sodium's aids in flower development and fruit set. Do not be fooled though, you can use either light throughout the life of a plant and get excellent results.

What size light should I purchase?
The first thing you need to do is figure out what kind of square footage you are dealing with. Do not just figure for the whole room figure out what the plant area is that you need to cover and multiply length x width to get the square footage. Now, you will want to try and achieve at least 30 watts per square foot. So if you have a 4 x 4 area which is 16 square feet and you multiply by 30 watts, you get 480 watts. So for a 4 x 4 area you will need to use at least a 430 watt light. Remember though that the amount of light required will depend on the plants because some plants like lots of light and some like low levels of light.

Do I need a ballast?
Yes. A ballast is required to start the lamp and to increase the voltage required to run the lamp. The ballast is responsible for starting the lamps by providing a high, fast charge of electricity. After the bulb lights, the range of voltage and current are controlled by the transformer which is why the bulbs operate so efficiently.

Are HID lights efficient?
Yes, very efficient compared to standard incandescent bulbs found in your house. For example one 1000 watt sodium bulb produces as much light as about 87 standard 100 watt incandescent bulbs.

Can I interchange bulbs between systems?
No. You should never interchange bulbs between systems unless they are specifically made to do so. Lots of people ask if they can use a 250 watt bulb in a 400 watt system and the answer is definitely not. You could put yourself at risk by doing something like this because the bulb could become unstable and explode. You should also never put Halide bulbs in a High Pressure Sodium system because the ballast's are only meant to run the type of bulb they are rated for and a Halide bulb in a Sodium system could overheat and explode also. There are conversion bulbs manufactured that are High Pressure Sodium bulbs that are meant to run off of a Halide ballast. But once again only put the bulb in a system it is rated for.

Do these lights require any special wiring?
No. All systems manufactured by Greentrees are completely wired and just need to be plugged into any grounded wall outlet. Custom voltages can be built into ballast's per customer request (208v, 240v, 277v). Do not attempt to change the voltage of the ballast unless you are an experienced electrician. Connecting the wrong wires could result in a fried ballast or bulb, and even worse a fire.

What kind of plants can be grown using hydroponics?
Almost any type of plant can be grown using hydroponics some are just more delicate than others. Usually if you can produce ideal environmental conditions the hydroponic plants will be far superior to plants from the same stock grown in soil.

How often should I change my nutrient solution?
There really isn't an amount of time that should be used to determine how often you should change your solution. A good rule of thumb to follow first of all is to top your reservoir off with fresh water without any nutrient added. This is because you will lose water to evaporation and plant uptake but the strength of the solution does not necessarily drop with the level of the water. So, in some cases as the reservoir water level drops the solution concentration actually goes up or gets stronger. So, add only fresh water and then adjust your pH accordingly. Try and keep a record of how much water you are putting in the reservoir to top it off and once the amount of water added equals half of the reservoir capacity it is time to change the solution and rinse the reservoir and growing medium. For example if you have a 20 gallon reservoir and over the course of 12 days you have added 10 gallons of water, then it is time to change your solution.

Can I transfer plants from soil to hydroponics?
Yes, you can all you need to do is wash the roots of the plant by dipping in water and try to remove as much of the soil matter as possible. Be very careful with the delicate roots so the plant doesn't go into too much transplant shock. After the roots are somewhat clean go ahead and pot the plant in any of your favorite hydroponic media and begin a standard watering regimen with a touch of B-1 in the solution for a week or so to aid in the recovery from transplanting.

Do plants grown using hydroponics taste better than plants grown in soil?
Quite often this is the case because the plants grown utilizing hydroponics have all the essential nutrients readily available to the plant. In soil the important micro nutrients are often locked away in the soil where the plants cannot take full advantage of these minerals. That is why hydroponics is superior because the grower has complete control over what minerals the plants are feeding on and in what quantities. This advantage over soil often produces produce that is far superior in taste, color, size, and nutritional value.

What is the difference between Aeroponics and Aero-Hydroponics?
There is a very simple definition of the difference between these two methods of growing. Aeroponic systems have plants which roots dangle in the air and the roots are sprayed with nutrient water. In an Aero-Hydroponic system there are roots that dangle but half of the roots dangle directly into water and the other half are sprayed with nutrient water. The spraying action keeps the standing water moving and circulating at all times which works excellent to get oxygen infused water to the roots. This Aero-Hydroponic method has proven to work incredibly for rooting cuttings and all other stages of growth as well.

Why does an ebb and flow tray system have two fittings?
First of all the common names of those two fittings are a fill/drain fitting and an overflow fitting. The fill/drain fitting is a fitting that is attached to the pump and serves as the inlet for the water filling the tray and also serves as the outlet for the water to drain back into the reservoir. The overflow fitting consists of a number of different plumbing parts and acts as a watering level regulator. The concept is quite simple... you have a tray that is suspended somehow, or sitting on top of, a reservoir. Now the pump turns on and begins pumping water into the tray and the pump will stay on as long as the grower has determined the watering cycle should be (usually 30 min.). As the water level rises in the tray it reaches the top of the overflow fitting which then allows the water to spill back down into the reservoir. So you have now filled the tray with water and you are maintaining that watering level by means of the overflow fitting, which does not allow the water level to rise any higher. Now when the pump is turned off the water begins draining by means of gravity back down through the fill/drain fitting, and through the pump, into the reservoir. The height of the overflow is decided by the containers or growing media being used. You only want the water level to rise and submerge about 50% to 75% of the medium or containers. This is to keep the medium or containers from floating and/or tipping over.

How often do I need to water my plants in an ebb and flow system?
Watering will all depend on the type of plants being grown, the size of those plants, and what type of medium you are using. As you know plants are very particular about being over or under-watered so this is an important question. First you need to determine if the medium you are using is absorbent or repellant. If you are using Rockwool you are dealing with an absorbent medium while Hydrocorn is a good example of a repellent medium that doesn't hold a lot of water. You want your medium to be moist but not drenched and you want your medium to dry out somewhat between waterings. So, if you watch your plants before and after waterings it will be very easy to tell if you are watering too much or too little. If your plants wilt before you water, but perk up immediately after watering, you may want to water a little more often. If your plants wilt just after watering than you are watering too much, and you should allot a little more time in between waterings. A good general rule of thumb is to start plants being watered about 2 to 3 times a day and increase as plants show signs of needing water.

How long should I water the plants for in an ebb and flow system?
In an ebb and flow system you are flooding a tray or pot full of nutrient solution to feed the plant or plants in your system. You do not want to keep the roots flooded for too long or you will risk drowning delicate roots. A good rule of thumb for watering in an ebb flow system is to water just long enough to completely flood your tray or pot with nutrient solution and then let the system drain. Most readily available timers have 30 minute increments so you may have to flood the tray for a little longer than it takes to reach the overflow level. This is fine as long as you do not keep the roots completely submerged for longer than an hour. Roots like oxygen, and keeping them submerged for too long cuts off the oxygen supply and can have fatal effects on your plants. So just remember to water only long enough to fill the system completely, and don't keep the roots submerged for too long.

What CO2 system is right for me?
The deciding factor in this problem is almost always heat. CO2 generators burn either natural gas or propane to produce CO2. The combustion of these fuels produces CO2 as a byproduct. Now the downfall of the generators is the heat that is produced in the process. While the generators are on they can raise temperatures in a grow room considerably. The nice thing about generators is the availability of propane or natural gas and the price of gas is considerably less than CO2. On the other hand, CO2 regulators are hooked up to CO2 tanks and regulate the amount of gas being emitted through the use of a timer and a flowmeter. You set the Cubic Feet per Hour (CFH) on the regulator and open the solenoid long enough to charge the room with CO2 up to the desired PPM using the timer to control the intervals. CO2 regulator type systems do not produce any heat at all but are more expensive to maintain then the generator systems since the price of CO2 is much higher than propane or natural gas.

What is the difference between Miracle-Gro and other commercially available fertilizers and hydroponics nutrients?
Most of the fertilizers readily available are very general purpose mixes that do not work well for all types of plants. The nutrients that we sell are made specifically for plants grown in hydroponics systems that utilize sterile growing mediums. Most commercially available fertilizers are meant for fertilizing plants grown in soil and do not contain all the necessary trace elements. Our fertilizers contain all those trace elements, and are also made to be very soluble so that the plants can easily uptake the nutrients from the watering solution. Those other fertilizers will work to grow plants but they cannot compare to the results you will experience with our nutrients. Most commercially available fertilizers are like junk food for your plants giving you quick results that do not last very long.

What is the desired temperature range for the nutrient solution?
The optimal temperature of the nutrient solution should be in the range of 65 to 75 degrees Fahrenheit. Letting water stand uncovered in a container overnight will help dissipate any chlorine in the water before you add it to the reservoir.

How much electricity will I save running a grow light 240 volt?
There is no energy savings from running your lights at 240 volts. That is a misconception that many people have. The main advantage is the fact that you can run more lights on one electrical circuit. For example if you run a 20 amp 120 volt circuit, you can only run two 1000 watt lights on that circuit. If you were to wire the circuit up for 240 volts you can run four 1000 watt lights on that circuit. This makes for a lot less wiring but does not save you on your electricity bill because each light still uses the same amount of watts. More Info: Watts cheaper 110 or 220?

How can I tell if my seeds are viable?
This can be accomplished by presoaking your seeds. Fill a shot glass with distilled water and place your seeds in it. After 24 hours the viable seeds should have sank to the bottom. Those still floating are most likely not viable and will not germinate.

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