Hydroponics is simply the growing of plants without soil. Instead, plants are grown in an inert medium (or none at all) and an oxygenated, balanced nutrient solution is delivered to a their root systems. That's it!

Why does Hydroponics produce such fantastic results?

By giving a plant the exact nutrients it needs we accomplish several things:

#1 We give it a perfect diet. In nature this is next to impossible, so when this actually happens, plants GROW & GROW & GROW.

#2 When we GIVE the plant it's food it doesn't have to go out looking for it. HUH?.....Yes, plants actually expend energy looking for food by growing huge root systems. If the plant doesn't have to waste energy looking for food, it puts all of it's effort into the parts above ground. The results are rapid, large healthy growth and massive fruit and flower production.

#3 By necessity, hydroponic systems are automated. This removes the negative human influence from plant cultivation. Specifically, forgetting to water, or watering too much.

How do I grow my plants hydroponically?

Fortunately, many methods of hydroponic marijuana growing have been invented throughout the years - from painfully simple to slightly complex. All you need to do is select the system that meets your needs and build it. As luck would have it, all of the systems that have been invented use very basic items assembled into very basic mechanisms. There is practically no method you cannot construct at home with no more than simple hand tools and commonly available parts.

Nutrients

All plants, whether grown hydroponically or in soil, need 16 basic elements to grow. Most of us are familiar with the top three that are consumed by plants. These elements are called the Macro-Elements and they are Nitrogen Phosphorous and Potassium, they are abbreviated N P K. You probably have seen these letters on bags of common fertilizer.
The other 13 elements are grouped together as the Micro-Elements. Most people are not familiar with these elements because we have always counted on them being present in the soil, which works for the most part.

Preformulated Nutrients: This is really the best option for the hobby to small farm hydroponic grower. You can be assured that all of the necessary nutrients are present and available to the plants. All you have to do is mix a predetermined amount of concentrate with water and add it to your system. If you want to be successful as a first time hydroponic grower, use a ready made nutrient specifically for hydroponics.
Preformulated Nutrients come in the forms of 1-part powders, 2-part powders, 1-part liquids, 2-part liquids, & 3-part liquids. I have found that nutrients are pretty much nutrients, with the exception of the General Hydroponics 3-part flora series. This one nutrient system really stands out above the rest, it gives the best results by far. You can customize the mix for specific crops and different phases of the crop (i.e. one mix for vegetative growth and another for flowering/fruiting phases of growth).

Formulating your own: Once you have some experience with hydroponics and you are producing large crops of a specific plant, you may want to look into formulating your own nutrients. Since all plants do not consume the same amounts of nutrients (individual elements) you can possibly save yourself some money by making very specific formulas for your crop. This involves a good amount of chemistry knowledge, some lab equipment and each of the 16 individual elemental nutrients. Many crop specific formulas exist from others' research, all you have to do is find the right recipe and mix it up. Over time you will probably adjust this formula to match your growing conditions and crop more closely. Mixing your own is best left to the more experienced who are producing large amounts of one crop (i.e. 1/4 acre on up).

Miracle Grow: Many people insist on tying to use miracle grow plant food as a hydroponic nutrient. It is true that this is great stuff for soil, I personally use it on my flowers and man do they freak out. Let me stress though, this stuff is not a complete nutrient for hydroponics. It does contain some micro elements, but not all. Your plants will start out fine using this, but eventually they will suffer from deficiencies. In the long run it is not worth the cost savings over a real hydroponic nutrient. The analogy would be something like buying a brand new corvette and then having the cheapest tires put on it and filling up with the cheapest Circle K gasoline. You will not even come close to getting the performance that is possible.

Nutrient Additives

There are quite a few hydroponic additives on the market. They mainly consist of combinations of kelp extracts, bone meal and blood meal. They are commonly sold as "Organic" boosters just to hook the "green" crowd. They are supposed to supply enzymes, hormones, vitamins, amino acids, sugars, and plant acids that can't be supplied by hydroponic nutrients. I believe that there are some merits to using these additives, but many of the claims made by these products are UNFOUNDED and UNTRUE. I have tried the "Earth Juice Catalyst" and I THINK that I saw a performance increase, but nothing major. In the future I will perform an experiment with a control group of plants to see how this stuff really performs.
One additive that falls in it's own class is the "DynaGRO PRO-TEEKT". It is a potassium and silicon supplement that is supposed to help increase resistance to pathogens, increase resistance to heat stress and build stem strength. I have yet to try this product.

pH

pH is simply the measure of the acid content of a solution. The pH scale runs from 1 to 14, 1 being very acidic, 7 is neutral, and 14 is very basic. pH affects the ability of a plant's roots to absorb nutrients. The range in which nutrient absorption is best is from 5.8 to 6.5. It is very important to maintain this range.
Measuring pH: You can measure pH either chemically or electronically. Chemical test kits cost about $8 to $18, they are accurate but you have to replace them periodically because the chemicals are consumed. Electronic methods typically are packaged as a pen that you simply dip into the solution and the pH is read out on a digital LCD display. pH pens cost about $65 to $100, they are fairly accurate and must be calibrated periodically. The benefit is ease of use and they don't wear out - a wise investment.
Adjusting pH: To lower pH add acid. The best acids to use are phosphoric, nitric, and sulfuric acid, these acids disassociate and free up phosphorous, nitrogen an sulfur respectively. Nitrogen, Phosphorous and Sulfur are all elements that plants need for growth. I have heard of people using Distilled Vinegar for pH adjustment, this seems a bit sketchy to me but I suppose it would word in a pinch.
To raise pH add a base. The bases used in hydroponics are Potassium Hydroxide and Sodium Hydroxide. These disassociate and provide Potassium and Sodium, respectively. Another pH up "elixir" that I have heard of is baking soda - personally I think this is a bad idea.
TIP! When adding acid or base to adjust your nutrient solution, add small amounts at a time and wait about 1/2 hour to take a measurement. The closer your pH is to 7, the less acid or base it takes to effect change. This change takes place exponentially, for example: it can take two milliliters of acid move the pH of 25 gallons of nutrient from 7 to 6. From 6 to 5 it can take 8 milliliters, from 5 to 4 it can take 500 milliliters. BE CAREFUL and make changes slowly.

Making your own pH adjusting solutions: One quart of acid or base from General Hydroponics retails for about $7.00. This is the biggest rip off in the hydroponic business! It takes about $10.00 of concentrated acid or base to make 2000 gallons of pH adjusting solution. Subtract packaging and shipping and you'll see that they turn $10 into $4000. OUCH!!!!!

Coming soon I'll have instructions for mixing your own solutions from concentrated acids and bases that you can buy in almost any town over-the-counter.

Organic Nutrients (??????)

With the relatively recent green movement the concept of "Organic" food production rings louder and louder every day. "Organic" guidelines prohibit the use of any refined chemicals in food production. The result is fertilizers derived from compost and animal waste.

Naturally people want to try to apply these principles to hydroponics in the form of a teas made from compost and other natural ingredients. This seems logical but the result is counter productive when used in a hydroponics environment. To understand why, we must first understand what nutrients are and how they are absorbed by plants.

Plants rely upon sixteen basic chemical elements for food - Nitrogen, Potassium, Phosphorus, Calcium, Hydrogen, and Oxygen are just a few. These elements must be in a form that can be absorbed by a plant. This form is a chemical salt - a very basic chemical compound containing one of the sixteen elements and a complementary element that forms a salt. These elemental salts are what is absorbed from the soil by the plant's roots.

So, the big question is - In the natural "organic" cycle of things how do these chemical salts get into the soil? Let's start with organic material (compost) and follow it to absorption by the plant. A bit of compost contains complex organic chemical chains that contain the elements for the chemical salts that eventually will be absorbed by a plant. At this point these complex chemical cannot be used by a plant. When the compost gets mixed into the soil it starts to be acted upon by soil born bacteria. This bacteria is what breaks the organic material down into the chemical salts that can be used by plants.

Organic material

+

Soil Born Bacteria

=

Nutrient Salts

Mother Nature uses bacteria to refine organic material into inorganic chemical compounds for plant absorption. In a hydroponic system sufficient bacteria are not present for this critical conversion, instead we must provide these refined chemicals directly to the system.

For those who insist that they can do it "organically" there are some "organic" nutrient mixes available for you to try. They typically produce limited results that I believe is entirely counterproductive to the hydroponic philosophy. I suggest that if you want to grow organically, do it in the dirt. Supplement the hell out of your soil with natural fertilizers and you will get excellent results. I do this in my own dirt garden and everything grows wonderfully.