by Ed Rosenthal
WATER ALKALINITY
The pH of pure distilled water is very unstable and has no buffering ability. The addition of a tiny amount of an acid makes it very acidic and a small amount of a base makes it alkaline. Our tap water contains minerals that it has picked up while percolating through the earth or hanging out in a reservoir. These minerals affect water’s alkalinity. Alkalinity is a measure of water’s ability to buffer acid, that is, resist change in pH when acid is added to it. The presence of Ca and other alkaline minerals such as potassium (K), buffers the water by neutralizing acids when they are added to it. Water with a small amount of Ca or other alkaline minerals has little buffering ability. As the alkaline mineral content increases so does its buffering ability. When there is too much buffer present alkalinity increases and large amounts of acids are required to change the pH.
Acceptable pH range for soil gardens: 5.5–6.5. Optimum pH levels are 6.0-6.3.
Alkalinity is tested by measuring the ppm of your water before adding nutrients or pH adjuster. Water with a ppm of 125-175 generally has enough Ca to act as a buffer, without having so much alkalinity that the water is hard to adjust.
Water that has a low Ca content can be adjusted by using Cal-Mag, available from many fertilizer companies. First add the Cal-Mag if needed; then adjust the pH. Then add fertilizers to the water if needed; then adjust the pH.
Every water district provides an annual water report. Below is the portion that concerns calcium (Ca), magnesium (Mg), potassium (K), alkalinity and pH. Other portions list contaminants, pollutants and other aspects of water quality.
The symbol mg/L is an abbreviation for milligrams per liter. There are 1,000 grams in a liter and 1,000 milligrams in a gram. Therefore, one mg/L also represents 1 ppm. (It’s a pretty convenient system. The United States should try it some time.)
Let’s examine the water coming from the Orinda reservoir, which services Berkeley, Oakland and several other cities in the San Francisco, California, East Bay Area (See Water Quality Annual Report, next page).
CO2 dissolved in the water lowers its pH. CO2 forms carbonic acid when it is in solution with water.
HYDRO-WATER SYSTEM
Acceptable pH range for hydro systems: 5.6–6.4. Optimum pH levels are 5.8–6.2.
Bicarbonate and carbonate equivalents: The first two categories, totaled together, show the total alkalinity. Ca, K and sodium (Na) all raise the alkalinity.
Calcium: levels vary between 4-20 ppm. This is too low a concentration for healthy plant growth and must be raised by increasing the ppm to 125-175 using Cal-Mag or calcium nitrate (CaNO3). CaNO3 is dissolved easily. It contains nitrogen (N), so it should not be used during flowering. Decrease other N fertilization when using it in the vegetative cycle.
Hardness: Hard water has high mineral content, usually mostly Ca and Mg, as compared with soft water. In this water, however, the K and other minerals play an important role. Sometimes iron (Fe) is also present, but not in this water.
Excessive calcium in the water is a leading contributor to nutrient lockout. Reverse osmosis systems purify water and neutralize pH. Aqua Engineering Reverse Osmosis systems have a membrane with a 98% rejection rate, which maximizes the plant’s potential to absorb nutrients.
A PPM/EC meter determines if the water is too hard which can make nutrients unavailable to the roots. PPM and pH meters are essential gardening tools. This one by Hanna (above left) is convenient because it measures pH, EC, and PPM. It recalibrates easily. Without a meter, water and nutrient decisions are guesswork. Right: Add pH Down to a solution that is too base, such as this filtered water.
Moisture meters and pH test kits allow the gardener to maximize the efficiency of the nutrient uptake of the plant.
One way to “test” the water is to use soap. It lathers easily in soft water but not in hard. Use a “simple” soap. “Modern” soaps often contain water-softening agents.
There are a number of factors that determine water hardness including temperature and pH, but generally speaking, water hardness corresponds with mineral content. Here are the ranges:
•VERY SOFT: 0-70 ppm—Much too little Ca/mineral content (EBMUD water falls into this category.)
•SOFT: 70-140 ppm—This falls in the low end of an ideal level. Add Ca to the water.
•SLIGHTLY HARD: 140-210 ppm—OK
•MODERATELY HARD: 210-320 ppm—the lower end of this spectrum is OK; however, the high end has too much buffering activity.
•HARD: 320-530 ppm—Mineral content must be lowered or accounted for in formulating fertilizers.
•VERY HARD: >530 ppm—Mineral content must be lowered or accounted for in formulating fertilizers.
There are several ways to handle high mineral content:
•Configure fertilizer to use nutrients that are found in the water and have raised its alkaline content as well as its total ppm.
•Reverse osmosis. This filters water clean by driving it through a tiny membrane. Osmosis water can be combined with tap or source water to create a mix that has a ppm of about 150.
East Bay Municipal Utility District Annual Report 2009
OTHER WATER QUALITY PARAMETERS Orinda
Alkalinity, bicarbonate (mg/L as CaC03) 20.2-36.4
Alkalinity, carbonate (mg/L as CaC03) 0.5-0.6
Calcium (mg/L) 4-20
Hardness (mg/L as CaC03) 15-78
Magnesium (mg/L) 0.8-5.6
pH (pH units) 8.2-9.3
Potassium (mg/L) 0.5-1.3
Silica (mg/L) 8.3-11
Sodium (mg/L) 5.5-19
The table above provides useful information for certain industrial and home applications. Information on water hardness in “grains per gallon”can help improve the function of cooling equipment and other process applications. To convert the hardness values into grains per gallon, divide the values shown in the tables in milligrams per liter by 17. For example, water hardness in areas served by the Orinda Water Treatment Plant had a range from 15 to 78 mg/L or 0.9 to 4.6 grains per gallon.
•Heat the water. Sometimes the calcium and other minerals are held as a carbonate or bicarbonate. In either case part of the carbonate portion of the molecule contains carbon dioxide. As water temperature increases it holds fewer gasses so the CO2 evaporates, leaving the Ca in the water. The calcium is no longer soluble so it precipitates, forming scale on the container. If white or tan chalky deposits form when you boil water or appear over a period of time, it is an especially good candidate for this treatment. Immediately pour the water from the container because as it cools it absorbs more CO2, which again combines with the minerals, dissolving them.
•Specialized non-chemical hard-water treatment systems.
Magnesium (Mg): Magnesium is dissolved as water traverses Ca bearing rocks and soil that also hold Mg. Notice that it ranges from 0.8-5.6 ppm. This is only a fraction of the plant’s needs so it must be supplemented.
When you irrigate the plants make sure that you don’t shock the roots with water that is either too cold or too warm. Make sure that the water is in the temperature range of 65-75° F (18-24° C).
pH: The pH is very alkaline because of the Ca in the water. However, since it contains few minerals its pH is sensitive to the addition of acids. A little pH Down goes a long way
Potassium (K): The amount of K dissolved in the water has hardly any effect on plant nutrition. However, it does slightly affect pH and alkalinity.
Silica: Plants readily absorb dissolved silica and hold it between their cells. It toughens the plant, strengthens the stem, and makes them more resistant to environmental stresses and insects.
Sodium (Na): Sodium is a portion of table salt, NaCl. It is dissolved in tap water as a result of geologic conditions and human interaction. It varies seasonally. This is a low number. Sodium, K and Ca dance in a chemical minuet regarding plant uptake. When levels get too high it affects uptake of these salts.
ASK ED: Marijuana Questions
USING BOTTLED WATER
To make an intelligent decision regarding irrigation water, obtain a report from your local water department. It will detail the water’s pH, dissolved solids and pollutants. Then you can determine whether the water is suitable for the plants or if it should be treated or substituted with water from another source. One element to examine is calcium. Some hydroponic fertilizers don’t contain much of it. If the water also has only small amounts you may need a calcium booster.
If you fed your plants Aquafina you might be supplying them with the same water they were receiving from your tap. Aquafina bottling plants use filtered tapwater, so the qualities of the waters, that is, the dissolved solids, pH and pollutants, vary by region. The brand is owned by Pep-siCo. Coca-Cola’s brand from the tap is Dasani. If the water says drinking water, rather than mountain spring, rest assured it comes from the tap. Unlike municipal water that you can obtain a report on, the bottled waters don’t list the water’s contents. To find out what’s in them you’d have to have them tested.
The amount of dissolved solids in bottled waters differs so it is impossible to make general statements about them.
In Europe bottled waters list their ingredients. Look for ones that contain at least 15 ppm calcium
NUTRIENTS AND FERTILIZERS
Photo: Rachael Szmajda
Prepared fertilizer mixes are designed to ensure that plants receive the essential nutrients required to reach their maximum potential. Once the plant is in the ground, or a container, the two easiest and most reliable ways to meet the plant’s needs are to use a prepared hydroponic fertilizer, a liquid organic fertilizer, or compost teas. Hydroponic fertilizers are blended as balanced and complete nutrient formulas. Non-hydroponic fertilizers often contain only macronutrients—nitrogen (N), phosphorus (P), and potassium (K). Organic fertilizers, such as fish emulsion, guanos and manures, and many blends of organics, contain additional trace elements found in the organic matter from which they are derived. Fertilizers may contain an incomplete menu of nutrients; always check the labels.
Most indoor plant fertilizers are water-soluble minerals. A few of them are time-release formulas mixed into the planting medium as it is being prepared. Plants grown in high quality soil mixes can typically get along using basic fertilizers, while plants grown in unenriched soilless mixes definitely require micronutrient enrichment plus calcium (Ca) and Magnesium (Mg).
Dolomite is composed of calcium magnesium carbonate CaMg(C03)2 and is a good natural supplement. To ensure a well-balanced diet of nutrients, many cultivators mix several products into a solution, or switch fertilizer formulas between feedings.
Mixing products from different companies can be risky since the formulas are may have minerals that interact adversely and create a nutrient imbalance. Choose proven products from reliable and established companies and follow their recommendations.
Plants grown in a nutrient-rich medium with compost, manure, or time-release fertilizers may need no additional fertilizing when planted in a large enough container or outdoor garden. Additional nutrients can be administered in supplemental amounts if the plants begin to show deficiencies.
Demand for critical nutrients, such as nitrogen (N), phosphorus (P), and potassium (K) varies with the growing conditions and changes during the plant’s life cycle. Marijuana uses more N during the vegetative cycle (before flowering) than in later stages. The plant’s use of P increases when it begins to flower, while the need for K increases after fertilization to aid flower formation and seed production.
Your plants’ N requirements also vary with light intensity and temperature. Plants growing under hot conditions should be given 10-20% less N, to prevent the thinning and weakening of stalks. Plants transpire, or sweat, on warm days and use extra water, concentrating nutrients. By diluting the nutrients a bit, they won’t overdose when they use water for transpiration.
Give plants in cool or cold regimens 10-20% more N because they will not be absorbing as much water. Under intense light conditions use more N and, conversely, less N in low-light conditions.
Teas, made by soaking organic matter or compost in water, enhance the plant’s ability to absorb nutrients and fight off diseases and insects. Worm castings, compost, and commercially prepared tea formulas are the most popular. Some hydroponic stores brew teas on site. Live compost tea must be brewed with a lot of oxygen or airflow. Without proper aeration compost tea will become infected by anaerobic bacteria which is a source of disease. Other ingredients used for teas are composted manures, blood meal, coffee, plant meals, minerals, ground rock, and oyster shells. The nutrient value of organic teas varies by ingredients and processor and are rarely well described well on their labels.
In hydroponic mediums, the plant is dependant on the gardener for all of its food. Some nutrient mixes are specialized to be multi-functional: they provide food and other services to the plant. BioBizz BioHeaven enhances the plants ability to absorb nutrients and boosts the antioxidant system of the plant, ridding it of toxins built up during periods of stress.
There are many organic fertilizer mixes on the market. Some are added directly to the soil or planting mix, while others are readily available formulas added to the water. The ingredients of all fertilizers are listed on the label as well as the elemental content by percentage.
Organic ingredients usually contain micronutrients as well as macronutrients. Make sure to look at the figures on the bag container when you purchase supplements. In addition to N-P-K, look to see if the product contains calcium (Ca), sulfur (S) and magnesium (Mg), which are crucial for bud formation. Most single ingredient organic fertilizers are not complete; they are more often used as a supplement or with other ingredients. Mixed ingredient balanced, complete, organic formulas are available both as soil additives used before planting, blended into the soil during the growing cycle, as well as water-soluble formulas that are used as plants are irrigated.
Organic fertilizers are usually not used in hydroponic systems because they ferment in reservoirs and are not completely soluble, so they clog up some systems.
DEFICIENCIES OF NUTRIENT ELEMENTS IN MARIJUANA
Most hydroponic formulas and other water-soluble fertilizers are formulated from minerals blended to create soluble salts. These dissolved salts are composed of molecules small enough to be absorbed through the root openings and are instantly available to the plants. These fertilizers can be used to provide nutrients either on a regular basis or a quick fix to resolve deficiency problems.
Fertilizers should be applied on the low side of recommended rates. To determine a plant’s nutritional needs, don’t only measure nutrients carefully, but use EC, PPM and pH testing devices. Even more important, look at the plants carefully to accurately diagnose the problem plaguing it. Throughout the plant’s life stages, it is critical to keep a close eye on the plants for minor symptoms of deficiencies.
In a hydroponic system, nutrients can get locked up and become unavailable to the plant if they aren’t delivered in pure, fresh, pH balanced water. Home and Garden Aqua Flakes Nutrients supply the plants with essential nutrients and cleans the water.
If added nutrients cure a deficiency, the plant usually responds in apparent ways within three to five days, depending on what element is deficient. Typically, the spread of the symptom stops and plant parts that were only slightly damaged begin to repair themselves, with the exception of calcium which is a non-mobile nutrient. Leaves and other parts that were slightly discolored may return to normal, although plant parts that were severely damaged, or suffered necrosis, will not recover. The most dramatic changes can be monitored through new growth—you will be able to differentiate plant parts that grew before and after the deficiencies were corrected. Maintain balanced nutrient solutions and keep an eye on new growth, this way, problems will become apparent quickly before they become serious.
OVER-FERTILIZATION
Over-fertilization occurs when a plant absorbs more fertilizer than it needs either as a result of excess fertilizing by the gardener, or when soil or soil less mixes become saturated with nutrients accumulated over time. The minerals fill extra-cellular space as well as change the chemistry in individual cells. An osmotic imbalance occurs when water is sucked from the plant by salt accumulation in the root zone.
Be wary of the numerous expensive supplements that are popping up at garden supply stores. These products are often designed more to improve the company’s profits rather than the quality of your crop. Growers have been growing great buds for decades using pure water, hydroponics and basic nutrients from reputable manufacturers. Some of the supplements are good, but often not necessary. Try the supplement with a few plants, but leave some of the same variety untested (controlled) because that is the only way to decide the effectiveness of the supplement. Many of the products are nothing more than very dilute phosphorous and potassium solutions.
COMPOST TEA
by Bonnie & Clyde
Compost tea is used for two reasons: 1) to inoculate microbial life into the soil or onto the foliage of plants, and 2) to add soluble nutrients to the foliage or to the soil to feed the organisms and the plants present.
Compost tea can be used any time that the organisms in the soil or on the plants are not at optimum level. Chemical based pesticides, fumigants, herbicides, and some synthetic fertilizers kill a range of the beneficial microorganisms that encourage plant growth, while compost teas will improve the life in the soil and on plant surfaces. High quality compost tea will inoculate the leaf surface and soil with beneficial microorganisms instead of destroying them. Compost tea is a liquid produced by leaching soluble nutrients and extracting bacteria, fungi, protozoa and nematodes from compost.