If you want your plants to excell, you will want to pay close attention to the nutrient solution. By monitoring nutrients, not only can you feed your plants the appropriate level of nutrition, but you can also maximize the nutrients available for uptake. Monitoring a solution ensures that you will not be underfeeding or burning your plants with too-high levels.

The pH value of a nutrient solution is a measure of the acidity or alkalinity of a solution. A basic, neutral solution is numerically equal to 7. The solution gets more acidic as the numbers decrease and more alkaline as the numbers increase. The ph scale ranges from 0 pH (very acidic) to 14 pH (highly alkaline). Pure water has a pH of 7, indicating that it is neither alkaline nor acidic, but neutral.

Different nutrients are absorbed at different pH levels. Most plants need a pH level between 5.8 and 6.5 for optimum nutrient uptake. If the pH is too low, nutrients are bound up and the roots are unable to absorb them. If the pH is too high, your plants may succumb to toxic salt buildup, limiting the ability of the roots to intake water and food.

Your pH will fluctuate and should be monitored regularly. It can be tested with inexpensive pH papers or with a pH Shaker Tester, or you may choose to use a pH meter. pH meters come in various degrees of sophistication and price. Some are handheld and need to be turned on each time they are used. They cost less but need more frequent calibration to keep them reading accurately. Other pH meters are continuous reading models which are always on and should be mounted next to the reservoir.

If you want to get real fancy, you can tweak the pH of your solution to allow more nitrogen in the growth phases and then readjust during the bloom phase for more phosphorous uptake. Most importantly you'll want to adjust the pH of your solution based on what plants you're growing.

pH Values for Different Hydroponic Crops
Plant	pH Range
Beans	6.0-6.5
Broccoli	6.0-6.5
Cabbage	6.5-7.5
Cantaloupe	6.5-6.8
Carrots	5.8-6.4
Chives	6.0-6.5
Cucumbers	5.8-6.0
Garlic	6.0-6.5
Lettuce	6.0-6.5
Onions	6.5-7.0
Peas	6.0-6.8
Pineapple	5.0-5.5
Pumpkin	5.0-6.5
Radish	6.0-7.0
Strawberries	5.5-6.5
Tomatoes	5.5-6.5

Adjusting the pH Level
The pH level of your nutrient solution will need to be adjusted if it is too low (too acidic) or too high (too basic.) You will want to keep pH Up and pH down handy in your grow area. Use very little at a time and stir the solution thoroughly. If you use to much of one then you will have to correct it with the other. The less you end up using, the better.

Be careful when handling these solutions as they can burn the skin.

By monitoring nutrients, not only can you feed your plants the appropriate level of nutrition, but you can also maximize the nutrients available for uptake. Equally important, you can be certain that your plants aren't undernourished. Both EC & TDS meters give an easy-to-read reference point of the conductivity of nutrient in solution.

TDS stands for Total Dissolved Solids and is measured in ppm or parts per million. One ppm is one part by weight of the mineral in one million parts of solution. I. In hydroponics TDS is estimated using a converstion from the measure of electrical conductivity (EC). TDS is currently the standard of measurement that most US growers use. This will probably begin to change in the future as hydroponic manufacturers begin changing their products to EC.

EC stands for Electrical Conductivity and is measured in mS/cm or miliSiemens per centimeter. An EC meter measures an electrical current in the solution and reads the conductivity produced from the motion of the mineral ions.Low conductivity means low nutrient concentration, often resulting in nutritional deficiencies and slow plant growth. High conductivity means more food for your plants. But be careful of not to get over zealous with the concentration of your nutrient solution; very high conductivity can burn or kill your plants

You may choose to monitor your nutrients with a handheld meter such as the Truncheon. You may also choose to use a continuous reading model such as the Nutri-Dip.

Nutrient controllers have been used for years by the commercial greenhouse industry, but they have only recently become available for small scale and hobby growers. Most nutrient dosers are capable of keeping both nutrient and ph levels at the correct values.

They are a little expensive, but if you plan on growing hydroponically for anything length of time, you may want to consider it. Your plants will greatly benefit because they will have a perfectly consistent nutrient source that will allow them to grow strongly without any setbacks. Your plants will not go for a few days here and a few days there with low nutrients or an incorrect pH level. Instead they will have exactly what they need, all the time.

Nutrient and pH controllers work through the use of set points and duration doseage times. It's a very simple concept. You program in the set points you wish for and the controller will dose the reservoir with a set amount of nutrient or pH adjuster to bring the reservoir readings to the right level.

There are two delivery systems that are available for these controllers. One is gravity fed with the use of solenoid valves. The second method is with a pump delivery system which eliminates the restriction on placement. (In gravity fed systems, the nutrients must be placed directly above the reservoir.) Both of these methods work well and once you have become acquainted with the parts involved, you will find them very easy to use.

There are several nutrient and pH controllers on our website. They vary in price and quality.

The system that we recommend (and use ourselves) is the IntelliDose from Autogrow Systems. It's an extremely easy system to use that controls your nutrient and pH levels on demand. The system is great for all sizes of gardens from the small hydroponic garden to a full scale hydroponic farm. With the IntelliDose you can simply calibrate your pH twice a month and designate settings, the IntelliDose does the rest for you.

The professional grower may be interested in the Nutridose II. This controller is the most industrial of those we offer and may be used with peristaltic pumps or with solenoid valves. It also has remote accessing capabilities, but it is slightly more complicated to use.

Although hydroponic formulas have come a very long way in providing total plant nutrition, many vital compounds and biological agents that are available to the plant in healthy soil are absent. When used correctly, metabolic enhancers can bridge the gap between organic and mineral nutrition. They can help the achieve full plant potential at every stage of growth. Metabolic enhancers and supplements can provide for

• Better seed germination
• Stronger seedlings
• Faster more vigorous clones
• Massive root systems
• Healthier vegetative growth
• Better resistance to pests & disease
• Bigger plants, higher yields

Many growers want to use organics in their hydroponic system. Although there are many brands of 'hydro-organic' nutrient on the market today, these nutrients are a bit more difficult to manage than 'regular' hydroponic nutrients. Organic nutrients (such as bat guano or bone meal or solutions made from these kind of ingredients) must be broken down before the plant can absorb the minerals. They work great in soil because of the micro bacteria which increase the rate of this process. In hydroponics there are no beneficial 'helpers' and so growth can be much slower as nutrients are not as quickly available to the plants.

Another thing to be wary of with organic nutrients is their propensity to clog drip emitters, tubing and pumps. It will be easier to grow organically using an ebb and flow system (with no drippers) as opposed to a drip system with many small parts.

Many growers use a regular hydroponic nutrient and supplement it with organic additives for the best of both worlds. For an excellent discussion on the organic/hydroponic debate, check out this article on General Hydroponic's website