Primer on Nutrients & pH

If you want your plants to excel, you need 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 the solution ensures plants will not be underfed nor burnt 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 equal to 7 on the pH scale. The solution becomes more acidic as the numbers decrease and more alkaline as the numbers increase. The pH scale ranges from 0 (very acidic) to 14 (highly alkaline). Pure water has a pH of 7.

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, plants may succumb to toxic salt buildup, limiting the ability of the roots to intake water and food.

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, adjust the pH based on what plants you’re growing.
Adjusting the pH Level

The pH level of your nutrient solution will need to be adjusted if it is too low or too high. You will want to keep bottles of pH Up and pH Down solution handy in your grow area. Use very little at a time and stir it into the nutrient solution thoroughly. The less you end up using, the better. If you use too much of one, you will have to correct it with the other. Be careful when handling these solutions as they can burn the skin. We sell three types of pH Up and Down solutions: Advanced Nutrients, the strongest stuff – made for larger reservoirs; Grow More pH solutions, which are cheaper and made for small to mid-size applications; and Earth Juice Natural pH Adjusters – All natural in a powder form.
Measuring the Nutrient Levels

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 parts per million (ppm). One ppm is one part by weight of the mineral in one million parts of solution. In hydroponics TDS is estimated using a conversion from the measure of electrical conductivity (EC). TDS is currently the standard of measurement that most US growers use. This will probably change in the future as manufacturers begin measuring their products in EC.

Like pH, TDS (and EC) meters come in two different forms. Handhelds, like the pH meters above, are easy to use, generally cheaper in price, and are great for checking multiple reservoirs with. We like the Hanna Primo TDS, an affordable entry-level ppm meter. The Hanna Waterproof TDS/EC Handheld Meter is also very nice. It is durable and easy to use, and is very accurate. Lastly, we like the “bullet-proof” Truncheon; it comes with a 5 year warranty, is easy to use, rarely ever breaks, and never needs to be calibrated. There are also continuous meters for reading TDS/EC only. However, most people interested in these want a “combo” meter…(keep reading).
Nutrient and pH “Combo” Meters

Most serious gardeners will eventually grow into using a “combo” meter which will measure both pH and TDS. The nicer units will also measure Temperature, and lend a higher degree of accuracy by compensating for the effect temperature has on the readings. Along with temperature & compensation, some of the nicer meters will allow a change in the Conversion Factor ( what the meter uses to convert readings from Electrical Conductivity to the TDS (ppm) value ). There are handhelds and there are continious Combo Meters available.
Nutrient and pH Controllers

Nutrient and pH controllers allows the grower to monitor and precisely control the nutrient solution, achieved through the use of set points and duration dosage times. You simply program in the set points you want, 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 available for these controllers. One is gravity fed, using solenoid valves. The second method is with a pump delivery system which eliminates the restriction on where it’s placed (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.

If you want your plants to excel, you will want to pay close attention to what is going on in your reservoir. By monitoring nutrients, not only can you feed your plants the appropriate level of nutrients, but you can also maximize the nutrients available for uptake. Monitoring insures against underfeeding or burning.
Order of Operations

It is very important that you follow these steps (in this order) when adding anything to your reservoir solution (nutrients, additives, etc.) Please note: whenever you add anything to a reservoir solution make sure that you adjust the pH last. Even if you just add water to a reservoir solution you still need to adjust the pH. There are certain exceptions to this order and it will be indicated on a given product label or set of instructions.

  1. Start Out with Purified (Reverse Osmosis) Water. We recommend a UV filter be employed on any incoming water into your reservoir. This insures that the starting water is pathogen free.
  2. Add MagiCal up to 150ppms. In the last 3 weeks of the Bloom stage you can add 50ppms of MagiCal.
  3. Add additives, one at a time, stirring well in between This includes anything that is not your main nutrient.
  4. Test ppms and see where you are at? You should only be at 37% (or just over 1/3) of overall desired ppms. (Ex. If desired ppms for given week are to be at 1500ppms then you will not want to have more than 550ppms with your additives added to your water solution (at this step))
  5. Add base nutrient (Examples of main nutrient: PureBlend Pro, Flora Nova, SensiBloom or Grow,Connoisseur, Any 3-Part Nutrient, etc.) as per directions (example: SensiBloom you add in equal parts A and B – If you add 100mL of A you will have to add 100 mL of B). Continue adding Nutrient until desired TDS is reached. (Ex. As in the previous example from step 3. the ppms after adding the additves were at 550. The desired ppms for that week are1500ppm. We now add 950 ppms of nutrient to the solution. CALL WITH QUESTIONS!!
  6. Adjust the pH of the reservoir solution.

Changing the Reservoir

A good rule of thumb is to always top off your reservoir with fresh water, without any nutrients added. You will lose some water through evaporation and plant uptake, but the strength of the solution doesn’t drop the with the level of the solution. Sometimes, as the reservoir water level drops the nutrient solution can become more concentrated. To avoid overdoing it, add only fresh water and then adjust your pH accordingly. The best way to know when it’s time to change your nutrient solution is to keep a record of how much water you’re putting in the reservoir to top it off. When the amount added equals half of the reservoir capacity, it’s time to change the solution and rinse the reservoir and growing medium. If you’ve got a 20 gallon res and over the course of 12 days you’ve added 10 gallons, it’s time to change your solution.
Cleaning and Sterilizing Equipment

Sterilizing your equipment is extremely important and it is often handled incorrectly. Many people make the mistake of using Hydrogen Peroxide for sterilization. This happens to be a poor oxidizer, unable to kill many different types of pathogens, and is only truly effective at a pH of 2.0. A better choice is Bio-Green Clean, an excellent organic enzyme cleaner. It is especially good at scrubbing out those hard-to-clean white trays.

Bleach, although not the most environmentally-friendly product, is an old favorite. It can kill anything, and is very cheap, making it hard to resist. Do NOT use it sparingly – make a very concentrated solution. Soak your gear for at least an hour, and let it run through all equipment (including pumps.) Scrub surfaces with a strong bleach solution. Then make sure to do multiple rinses with plain water to rid the trays of any residuals. When using strong bleach solutions, wear gloves and work in a ventilated area.
Water Temperature

Although expensive, nothing works better for controlling water temperatures than a water chiller. It is of critical importance for a healthy root zone that water temps stay between 66-68 °F. This does not mean that temperatures can sometimes be above or below this temperature, only that the solution should consistently remain in the 66-68 °F. range. At this temperature, the nutrient solution holds a good amount of oxygen, and the nutrient absorption rates are still high enough for most plants.
Reverse Osmosis “Purified” Water

Why would you drink purified water and not feed it to your prized plants as well? Reverse Osmosis (RO) water is purified of all contaminants, minerals, and chlorine, effectively cleaning the life-blood of your plants’ vascular systems. Coupling an RO water purification system like the Merlin Garden Pro or the Stealth 200 with a UV filter system ensures that your water is fresh and clean and also free of any pathogens.
Using Beneficial Biology to prevent Root Rot

There is a complex relationship between plants and the microbes that live in and make up the rhizosphere. As growers we we want to innoculate and promote healthy microbe colonies. Some of the more common varieties to look for are Mycorrhizae, Trichoderma, and Bascillus Subtillus. There are a plethora of products that help us in our endeavors, including Roots Excelurator (the Best Protection Product we have)Vermi-T, Piranha,Subculture, Tarantula, Voodoo Juice, and HydroGuard, to name a few. We even brew our own concoctions.
Enzyme Solutions

Small, yet amazingly powerful, enzymes have a variety of important benefits for the grower. There are many different enzymes and all have different functions. We are most concerned with two types of enzymes: those that accelerate sugar / resin production to create flavor and aroma, and those that break down dying and dead plant proteins (dead leaves and roots) into their component parts – amino acids, lipids and smaller molecules which can be reabsorbed by the plant and the beneficial microbes. This also prevents those proteins from becoming food for pathogens. Some of the enzyme solutions we like are Hygrozyme (for better, faster overall growth),Sensizyme, Cannazyme and MultiEnzyme for enzymatic breakdown of dying root tissue
The Other Route – Keeping a Reservoir Sterile

Some growers rely on “clean” growing environments, strong disinfectants, and products to sterilize the reservoir. This is harder than it sounds. Folks who have been growing in the same area for years might find that they are having root problems when they never had them before. Or a new grower might have them from the beginning. In any case, it can be tough to rid your area of pathogens once they have been introduced.

Zone: Comprised of monochloramine and essential oils know to ward off root disease. This is the strongest sterilizing agent that we sell. It is easy to use and works well at preventing root disease. Can be used at 2-3x strength to fight an infection. (Make sure to NOT add any beneficial microbes or enzyme solutions to the mix.)

Hydrogen Peroxide: Creates ozone in water, killing bacteria & adding oxygen to the system. Elevated levels of oxygen in water have proven to dramatically increase the speed of plant growth. Recommended (in HIGH concentrations) for cleaning as well.

UV – Filter: Use of a UV filter can greatly help win the battle against pathogens. As long as the nutrient solution is clear when it runs across the filter, (i.e. no organics,) any microorganism’s DNA will be torn apart.

PLEASE NOTE!! Both Zone and Hydrogen Peroxide offer protection and benefits. But NEITHER works well with beneficial biology or enzymes added to the reservoir. Hydrogen Peroxide doesn’t work well with anything organic.
Irrigation Pump

An irrigation pump is used to pump water from the main reservoir to the Hydroponic / Soil Delivery / Drip system. Since there are so many brands and sizes of pumps to choose from, it can be quite hard to figure out the proper size pump for your given system. It is best to talk to us about it first. (Also note: All pumps are not created equal. Even though two pumps have the same GPH rating doesn’t mean they will output at the same rate.) Make sure to ask a sales person about the differences.
Float valve or Float Switch

Float valves are a simple concept that can help insure a hydroponic system always has enough water. You’ll notice the float valve is attached to the right side of the reservoir, with a water line coming in. At first glance a float valve might seem difficult to use and operate, but in truth the concept is easy and accessible. Float valves work in a similar way to a toilet. When the water level of the reservoir drops, it causes the float valve to drop with it, thereby opening up the pathway for water to flow into the reservoir. When the reservoir is filled up again, the float valve rises back up with the water and closes off the pathway, thus restricting water from passing through. Float valves can be used to connect one reservoir to another, or they can be connected directly to a water filtration system directly such as The Merlin Garden Pro or the Stealth 200. In between the float valve and the incoming water line we like to put a ball valve (giving you more control of when the water is flowing into your reservoir.) We can help – Talk to us about installing a float valve. It is actually cheap and easy! This provides for automated water filling. We also believe in employing a slightly more sophisticated float – called a float switch; involving a watering timer. Inquire within!
More Aeration at the Root Zone

Most reservoirs need some form of aeration. Oxygen is very important for healthy roots and aerated water provides bonus oxygen. We suggest using either an air pump, air stone or venturi, or a combination of all three. None of these is depicted in the picture above. The other types of systems will need extra oxygen, depending on the type of growing media used. We suggest the biggest air pumps you can find! Your reservoir should be bubbling like a hot tub!
Draining the reservoir with the help of a “Drain Pump”

Since draining the reservoir is a regular event (about once a week), we suggest using a separate drain pump to speed up the operation. This pump should ideally suck from the bottom in order to assure complete and thorough drainage. Examples of good drain pumps are the Little Giant PE-1 for smaller reservoirs, the NK-1 orNK-2 for medium size reservoirs, and a Water Wizard hooked up to 3/4” hose line for larger reservoirs.
Keeping your Reservoir Temperatures Cool using a Water Chiller

A water chiller is one of the most over-looked and most needed component to a healthy reservoir. A water chiller assembly employs a submersible pump to move water through the chiller and back into the reservoir solution. Chillers can be set up to have a differential so that they are not always running. Ideal water temperature is between 66-69 deg. F. The chiller will bring the water down to 66 deg. F. and then turn off until the water is up to 68 deg. F. (We like EcoPlus Chillers or Frost Boxes over any other because they are well made, more durable and longer-lasting. Of the two, the Frost boxes are a large step above.)

What is PPM or TDS?

TDS stands for total dissolved solids and is measured in ppm or parts per million. One ppm is equal to one part of the total mineral weight in one million parts of solution. In a laboratory, the weight of TDS is found by allowing a liquid to evaporate and weighing the particles left over. In water culture, TDS is estimated using a converstion from the measure of electrical conductivity (EC). TDS is not exact – it depends on the conversion factor used, and different brand names can vary by as much as 600 ppm. 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.
What is 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 overzealous with the concentration of your nutrient solution; very high conductivity can burn or kill your plants.
How do I convert my readings from TDS to EC and vice versa?

To get the approximate TDS value, simply multiply the EC reading (in miliSiemens/cm) by 1000 and divide by 2. To get an EC value, multiply the ppm reading by 2 and divide by 1000.
For example if your EC is 1:

1 x 1000/2 = 500ppm

And if your ppm is 500:

500 x 2/1000 = 1EC
What is the best way to measure the amount of nutrients in a solution?

In Europe, EC has been used exclusively. In the US, most growers have been using TDS. The problem is that, as explained earlier, TDS is a conversion from EC, and different manufacturers use different conversion rates. Different TDS meters may show a discrepancy of as much as 600 ppm when reading the same solution. A few years ago, at the Hydroponic Merchants’ Association conference it was decided that the US industry would begin to switch over to EC. This switch over could take years. American growers still seem to want to use TDS meters most often and we supply a wide range of quality ones. Be sure when calibrating these meters to use the correct calibrating solution from the correct manufacturer.
What nutrient level should my nutrient be at?

For seedlings, your nutrient level should be between 400ppm (800ms) and 600ppm (1,200ms). For vegetative growth, the level should be between 800ppm (1,600ms) and 1,100ppm (2,200ms). For bloom, the level should be between 1,000 ppm (2,000ms) and 1,400ppm (2,800ms). These of course are very general levels