I've decided to start a thread all about water,
Now before you say to yourself, "Guineapig....Water you doing this crazy
thread for?" (hehe), I would like to point out just how important water quality
can be for maximizing the growth of the Cannabis plant. We'll talk about
everything water-related and especially how it applies to Cannabis plant
growth, including types of water, pH, watering methods, etc. Feel free to
join in the fun and add some interesting water-related stories or articles or
whatever you feel might help out!!!
(look!! I've taken a bath to start the fun!!!)
ok enough jokes.....let's get our feet wet:
Types Of Water:
There is no such thing as naturally pure water; all waters we drink contain dissolved solutes and many contain some microorganisms [965]. There are several forms that the water we drink may take, which vary subtly from each other; drinking water, spring water, tap water, natural mineral water and water preparations promoted with various health claims. Bottled waters are subject to international regulations but are not necessarily safer than tap water. Clearly, all such water must be drinkable, contain solutes (including those classed as contaminants) below the legally-allowed limits, to be bacteriologically safe and be subject to continued monitoring.
-Tap water Water, from any source, treated to meet legal and quality standards. It may contain low or moderate amounts of minerals depending on the source of the water (e.g. hard or soft water areas). This is the major water product with over a billion glasses a day being consumed in the US alone, although most domestic tap water is used for washing, flushing the toilet and through wastage. Often it is chlorinated, which ensures microbiological safety for long periods of storage and eliminates all risks from otherwise devastating diseases such as cholera and dysentery. Although chlorination has been shown to possibly produce potentially hazardous byproducts, the association between exposure and demonstrable adverse health effects is still unproven and the protection chlorination offers far outweighs this risk. Fluoridation of water (e.g. by adding SiF62-) for the purpose of reducing dental caries, is generally regarded as safe [966a]. However, groundwaters containing excessive amounts of fluoride (> 1 mg/liter) are widespead [966b]. The health claims for fluoridation remain contraversial [1048].
-Drinking water Water intended for human consumption and may contain disinfectants and/or other solutes within legal quality standards. Such bottled water is not necessarily better for health than tap water, as shown in 2004 when Coca Cola was awarded an Ig® Nobel prize for producing Dasani in the UK. Dasani was a bottled 'pure' water prepared from London tap water. It was found that it contained high levels of the carcinogen bromate, which is (and was) not present in the tap water. The bromate was introduced by reaction between the added ozone and calcium chloride containing calcium bromide during production (for background science see [1000]).
-Natural mineral water Water from a spring, artesian well or well that naturally contains dissolved salts [967]. It may be carbonated. It is characterized by its mineral content, which may vary between far lower to much higher than tap water, according to source. Mineral waters must be naturally safe with no parasitic or pathogenic organisms as they are not subject to disinfection. The presence of safe microorganisms is used as proof that no disinfection has taken place. Higher silica content distinguishes mineral water from surface (e.g. reservoir) water. The price of mineral water is over a thousand times that of quality tap water.
-Spring water Water from an underground aquifer, collected as it flows and bottled at source.
-Processed water with health claims
There is an increasing market in bottled water and domestic water processing equipment claiming that the water has considerable health benefits varying from more rapid hydration to cures for AIDS and cancer. Generally there are no proper scientific trials to prove these claims, only isolated testimonial evidence. Oxygenated drinks have been proposed to improve the immune status. However, a randomized blinded clinical study [968], although showing a transient moderate increase in oxygen radicals (using 6 mM O2) and signs of activation of the immune response, was not conclusive.
One factor often used to promote these ‘health’ waters is supposed greater cellular hydration or ease of hydration. It is unclear whether increased cell hydration is actually health-promoting. A recent paper has argued that this may be a determining factor in the initiation of cancer [969]. It has been found that cancer cells do have greater water with increased fluidity but the cause and effect relationship (i.e. whether increased cellular hydration initiates cancer or cancer initiates high cellular hydration) has not yet been established.
-‘Sports’ drinks Sports drinks [973] are intended to reduce fluid, mineral (e.g. particularly Na+) and energy imbalance due to exercise. The carbohydrate content and osmolality must both be low to encourage efficient hydration (i.e. the drink must be hypotonic (<280 mOsmol/L) or isotonic (~280 mOsmol/L)). Na+ ions (usually as NaCl) are a necessary ingredient as they stimulate both sugar and water uptake in the small intestine as well as replacing material lost by sweat. Hypotonic drinks give more rapid hydration but clearly contain less sugar and minerals. Chilling improves palatability so encouraging consumption. Some sports drinks contain ‘power’ ingredients such as caffeine or taurine, where there is patchy evidence of some sports benefit. These products are usually promoted with testimonials from athletes or sports teams, but without double-blinded trial evidence.
For the complete website, go here: http://www.lsbu.ac.uk/water/index2.html
Water Quality
Water quality
It probably goes without saying, but the water you use must be as clean as possible. For plants, however, 'clean' is a relative concept. Nutrients such as nitrogen, phosphate, potassium, etc. are always dissolved in water used for plant food. In any case, the concentrations the plants need of these materials make the water undrinkable for humans. In contrast to 100% distilled water, 'pollutants' are found in ordinary tap water. You can request a chart with data about the quality from the company that produces your drinking water. The hardness in degrees - the GH (German Hardness) - is also given. This is a measure for the amount of calcium in the water. Below, you have an example of this kind of water chart. Some of the 'pollutants' aren't 'pollutants' to plants, but actually fertilizing materials. To determine the water quality (and the plant foods you add), you need two types of meters. The first is an EC meter. 'EC' is the abbreviation for 'Electrical Conductivity'. Pure water, also called demineralized water, does not conduct electricity. When we add fertilizer to the water, or the water is 'polluted' in some other way, the water will indeed conduct electricity. Fortunately, home growers can make use of this property of water. With the EC meter, we can determine whether or not the concentration of nutrients in the water will provide for optimum plant growth. A high EC value means a high concentration of fertilizing materials, and a low EC value, a low concentration. Too high a concentration shows that you're over-fertilizing. As a result, your plants will dry out and burn. (By osmotic processes, water is drawn out of the plant; the leaves curl upwards or downwards.) The fertilizer concentration must be lowered by further diluting with water. Too low an EC value means a shortage of fertilizer. This decreases the growth on rockwool substrate. The EC value is given in millisiemens. 1.8 millisiemens is the optimal value for growing cannabis. The second type of meter is the pH meter. With a pH meter, you can determine the acidity of water. Most of us have measured the acidity of a solution at one time or another in high school. We did it with a litmus test. But the litmus test is not suitable for measuring acidity when growing hemp at home. The accuracy of this test leaves something to be desired. Actually, we can only estimate the pH value, to the accuracy of one pH point. We need greater accuracy for cultivating cannabis. The average pH meter used by aquarium owners is relatively cheap, and meets the requirements well. Generally, they're up to 0.02 pH points accurate. The ability to absorb nutrients depends on the acidity of the water. If the pH is too high or too low, the plants can't absorb some nutrients properly. Then deficiency disease occurs . The pH scale goes from 1 to 14. A solution with a pH between 1 and 7 is called 'acid', a pH of 7 is called neutral, and between 7 and 14, 'basic'. The lower the pH, the more acidic the solution (in our case: water). On the next page, you have a chart showing which nutrients plants can absorb best at each pH. You can read from the chart that cannabis plants like it if they receive water which is slightly acidic. The home grower must make sure that the pH of the water being used is approximately 5.8. The EC meter, as well as the pH meter, must be adjusted now and then. Special calibrating fluids are available for this operation. The temperature is also an important factor when calibrating an EC meter. The correct temperature is listed on the package of calibrating fluid. A pH meter has two set screws, and it must be adjusted to two values. The probe of the pH meter is first dipped into a calibrating fluid with a pH value of 7.0. Then, this value is set using one of the set screws. After that, the probe must be cleaned well, otherwise deviations will occur with the second calibration. Next, the probe is dipped in a calibrating fluid with a pH value of 4.0, and this value is set using the other set screw. It's important that the pH meter probe is kept moist. Depending on the type of pH meter, it may be stored in ordinary tap water, or in a special fluid supplied by the manufacturer. In the story about the EC meter, we've already indicated that the temperature of the nutrient solution influences plant growth. Cannabis grows best with a water temperature of 25 degrees Celsius. Below this temperature, the roots of the plant have more trouble taking up water and nutrients. Too high a temperature is not good either. That will kill the plants Tap water must be warmed up to 25 degrees C. Use a water thermometer to keep an eye on the water temperature. Warming the water is easy with the installation of a heating element in the nutrient tank. This equipment also comes from the aquarium world. Quality heating elements with thermostats are available for aquariums. For a 100 liter nutrient tank, you need a 100 Watt heating element; with a 200 liter tank, we recommend a 250 Watt element. Make sure the heating element is always kept under water; otherwise it will be destroyed. This means that you must never pump all the water out of the nutrient tank to the plants. When you want to take the heating element out of the water, always disconnect it first. Then, let it cool off for at least 15 minutes. Only then can you carefully take it out of the water. Any other way, you run the risk the element will crack. To prevent algae growth in the nutrient tank, it's important to add air to the water. We do that by means of an aquarium pump with an aerator attached. The aerator is connected to the pump, and placed at the bottom of the nutrient tank. The water in the tank becomes rich in oxygen by aeration, and is also kept in motion. This way, algae have much less chance to proliferate.
Guide to Watering Plants:
Indoor Plants - Watering
The main cause of death of potted plants is over-watering. Roots need both water and oxygen, and when surrounded by water, they cannot take up oxygen. These roots may rot and eventually the whole plant may die. The symptoms of over-watering and underwatering are similar. Both lead to poor root health, root decline and possibly death of the plant.
A common question from gardeners is "How often should I water my plants?" There is no pat answer to this question. The amount and frequency of watering depends on many factors, such as the plant species, its growth stage, its location, the type and size of its pot, soil mix characteristics and variable weather conditions.
There is a wide range of watering requirements for different species of plants. Plants with large or very thin leaves and those with fine surface roots usually require more frequent watering than succulent plants with fleshy leaves and stems that are able to store water. Some plants thrive under moist conditions while other plants grow well when kept drier.
Plants may slow in growth after a flush of new growth or a heavy flowering. During these periods and while it is dormant, a plant will need less water.
Water evaporates rapidly from the sides of a porous clay pot, which requires more frequent watering than nonporous, glazed or plastic pots. A large plant in a small pot needs water more often than a small plant in a large pot.
Different soil mixes require different watering schedules. Heavy, fine-textured potting media and those that contain a lot of peat moss hold more moisture than loose, porous mixtures of bark, sand and perlite.
A plant in a warm, dry, sunny location needs more frequent watering than one in a cool, low-light environment.
The rule-of-thumb is to water when necessary. The following methods may be used to determine when to water:
Touch the soil – The most accurate gauge is to water when the potting mixture feels dry to the touch. Stick your finger into the mix up to the first joint; if it is dry at your fingertip it needs water.
Tap the pot – When the potting mix in a clay pot begins to dry, it shrinks away from the sides of the pot. Rap the side of the pot with the knuckles or a stick. If the sound is dull, the soil is moist; if the sound is hollow, water is needed.
Estimate weight – As potting mixtures become dry, a definite loss in weight can be observed.
Judge soil color – Potting mixtures will change from a dark to lighter color as they dry.
There are a number of watering meters available to measure moisture in the soil, indicating whether water is needed. These products vary widely in accuracy. The readings can be influenced by factors other than soil moisture content. Fertilizer and soil type can affect the reading.
When watering is required, water thoroughly. Apply water until it runs out of the bottom of the pot. This washes out the excess salts, and it guarantees that the bottom two-thirds of the pot, which contains most of the roots, receives sufficient water. Don’t let the pot sit in the water that runs out. Empty the saucer.
Do not allow the soil to become excessively dry. If the salt level in the container is high, root damage may occur. If soil does become very dry and hard to rewet, use the double watering method. Water once and then again half an hour later; or place the pot in a sink or a bucket of water. Remove the pot when the soil surface is moist. Allow the pot to drain completely. If peat is allowed to dry completely, not only is it difficult to rewet, it also will not hold as much water as it could hold before it dried.
Do not water with hot or cold water. The water temperature should be between 62 and 72 °F.
Do not water plants with softened water because sodium and chloride will also be added to the soil mix, possibly causing plant damage.
Although wilting is often an indication of the need to water, it is not always so. Any injury to the root system decreases a plant’s ability to take up water, including root rot, which is caused by too much water. This inability to take up water will cause wilting, and under these conditions, watering may make the problem worse.
Excerpted from the South Carolina Master Gardener Training Manual, EC 678.
Now before you say to yourself, "Guineapig....Water you doing this crazy
thread for?" (hehe), I would like to point out just how important water quality
can be for maximizing the growth of the Cannabis plant. We'll talk about
everything water-related and especially how it applies to Cannabis plant
growth, including types of water, pH, watering methods, etc. Feel free to
join in the fun and add some interesting water-related stories or articles or
whatever you feel might help out!!!
(look!! I've taken a bath to start the fun!!!)
ok enough jokes.....let's get our feet wet:
Types Of Water:
There is no such thing as naturally pure water; all waters we drink contain dissolved solutes and many contain some microorganisms [965]. There are several forms that the water we drink may take, which vary subtly from each other; drinking water, spring water, tap water, natural mineral water and water preparations promoted with various health claims. Bottled waters are subject to international regulations but are not necessarily safer than tap water. Clearly, all such water must be drinkable, contain solutes (including those classed as contaminants) below the legally-allowed limits, to be bacteriologically safe and be subject to continued monitoring.
-Tap water Water, from any source, treated to meet legal and quality standards. It may contain low or moderate amounts of minerals depending on the source of the water (e.g. hard or soft water areas). This is the major water product with over a billion glasses a day being consumed in the US alone, although most domestic tap water is used for washing, flushing the toilet and through wastage. Often it is chlorinated, which ensures microbiological safety for long periods of storage and eliminates all risks from otherwise devastating diseases such as cholera and dysentery. Although chlorination has been shown to possibly produce potentially hazardous byproducts, the association between exposure and demonstrable adverse health effects is still unproven and the protection chlorination offers far outweighs this risk. Fluoridation of water (e.g. by adding SiF62-) for the purpose of reducing dental caries, is generally regarded as safe [966a]. However, groundwaters containing excessive amounts of fluoride (> 1 mg/liter) are widespead [966b]. The health claims for fluoridation remain contraversial [1048].
-Drinking water Water intended for human consumption and may contain disinfectants and/or other solutes within legal quality standards. Such bottled water is not necessarily better for health than tap water, as shown in 2004 when Coca Cola was awarded an Ig® Nobel prize for producing Dasani in the UK. Dasani was a bottled 'pure' water prepared from London tap water. It was found that it contained high levels of the carcinogen bromate, which is (and was) not present in the tap water. The bromate was introduced by reaction between the added ozone and calcium chloride containing calcium bromide during production (for background science see [1000]).
-Natural mineral water Water from a spring, artesian well or well that naturally contains dissolved salts [967]. It may be carbonated. It is characterized by its mineral content, which may vary between far lower to much higher than tap water, according to source. Mineral waters must be naturally safe with no parasitic or pathogenic organisms as they are not subject to disinfection. The presence of safe microorganisms is used as proof that no disinfection has taken place. Higher silica content distinguishes mineral water from surface (e.g. reservoir) water. The price of mineral water is over a thousand times that of quality tap water.
-Spring water Water from an underground aquifer, collected as it flows and bottled at source.
-Processed water with health claims
There is an increasing market in bottled water and domestic water processing equipment claiming that the water has considerable health benefits varying from more rapid hydration to cures for AIDS and cancer. Generally there are no proper scientific trials to prove these claims, only isolated testimonial evidence. Oxygenated drinks have been proposed to improve the immune status. However, a randomized blinded clinical study [968], although showing a transient moderate increase in oxygen radicals (using 6 mM O2) and signs of activation of the immune response, was not conclusive.
One factor often used to promote these ‘health’ waters is supposed greater cellular hydration or ease of hydration. It is unclear whether increased cell hydration is actually health-promoting. A recent paper has argued that this may be a determining factor in the initiation of cancer [969]. It has been found that cancer cells do have greater water with increased fluidity but the cause and effect relationship (i.e. whether increased cellular hydration initiates cancer or cancer initiates high cellular hydration) has not yet been established.
-‘Sports’ drinks Sports drinks [973] are intended to reduce fluid, mineral (e.g. particularly Na+) and energy imbalance due to exercise. The carbohydrate content and osmolality must both be low to encourage efficient hydration (i.e. the drink must be hypotonic (<280 mOsmol/L) or isotonic (~280 mOsmol/L)). Na+ ions (usually as NaCl) are a necessary ingredient as they stimulate both sugar and water uptake in the small intestine as well as replacing material lost by sweat. Hypotonic drinks give more rapid hydration but clearly contain less sugar and minerals. Chilling improves palatability so encouraging consumption. Some sports drinks contain ‘power’ ingredients such as caffeine or taurine, where there is patchy evidence of some sports benefit. These products are usually promoted with testimonials from athletes or sports teams, but without double-blinded trial evidence.
For the complete website, go here: http://www.lsbu.ac.uk/water/index2.html
Water Quality
Water quality
It probably goes without saying, but the water you use must be as clean as possible. For plants, however, 'clean' is a relative concept. Nutrients such as nitrogen, phosphate, potassium, etc. are always dissolved in water used for plant food. In any case, the concentrations the plants need of these materials make the water undrinkable for humans. In contrast to 100% distilled water, 'pollutants' are found in ordinary tap water. You can request a chart with data about the quality from the company that produces your drinking water. The hardness in degrees - the GH (German Hardness) - is also given. This is a measure for the amount of calcium in the water. Below, you have an example of this kind of water chart. Some of the 'pollutants' aren't 'pollutants' to plants, but actually fertilizing materials. To determine the water quality (and the plant foods you add), you need two types of meters. The first is an EC meter. 'EC' is the abbreviation for 'Electrical Conductivity'. Pure water, also called demineralized water, does not conduct electricity. When we add fertilizer to the water, or the water is 'polluted' in some other way, the water will indeed conduct electricity. Fortunately, home growers can make use of this property of water. With the EC meter, we can determine whether or not the concentration of nutrients in the water will provide for optimum plant growth. A high EC value means a high concentration of fertilizing materials, and a low EC value, a low concentration. Too high a concentration shows that you're over-fertilizing. As a result, your plants will dry out and burn. (By osmotic processes, water is drawn out of the plant; the leaves curl upwards or downwards.) The fertilizer concentration must be lowered by further diluting with water. Too low an EC value means a shortage of fertilizer. This decreases the growth on rockwool substrate. The EC value is given in millisiemens. 1.8 millisiemens is the optimal value for growing cannabis. The second type of meter is the pH meter. With a pH meter, you can determine the acidity of water. Most of us have measured the acidity of a solution at one time or another in high school. We did it with a litmus test. But the litmus test is not suitable for measuring acidity when growing hemp at home. The accuracy of this test leaves something to be desired. Actually, we can only estimate the pH value, to the accuracy of one pH point. We need greater accuracy for cultivating cannabis. The average pH meter used by aquarium owners is relatively cheap, and meets the requirements well. Generally, they're up to 0.02 pH points accurate. The ability to absorb nutrients depends on the acidity of the water. If the pH is too high or too low, the plants can't absorb some nutrients properly. Then deficiency disease occurs . The pH scale goes from 1 to 14. A solution with a pH between 1 and 7 is called 'acid', a pH of 7 is called neutral, and between 7 and 14, 'basic'. The lower the pH, the more acidic the solution (in our case: water). On the next page, you have a chart showing which nutrients plants can absorb best at each pH. You can read from the chart that cannabis plants like it if they receive water which is slightly acidic. The home grower must make sure that the pH of the water being used is approximately 5.8. The EC meter, as well as the pH meter, must be adjusted now and then. Special calibrating fluids are available for this operation. The temperature is also an important factor when calibrating an EC meter. The correct temperature is listed on the package of calibrating fluid. A pH meter has two set screws, and it must be adjusted to two values. The probe of the pH meter is first dipped into a calibrating fluid with a pH value of 7.0. Then, this value is set using one of the set screws. After that, the probe must be cleaned well, otherwise deviations will occur with the second calibration. Next, the probe is dipped in a calibrating fluid with a pH value of 4.0, and this value is set using the other set screw. It's important that the pH meter probe is kept moist. Depending on the type of pH meter, it may be stored in ordinary tap water, or in a special fluid supplied by the manufacturer. In the story about the EC meter, we've already indicated that the temperature of the nutrient solution influences plant growth. Cannabis grows best with a water temperature of 25 degrees Celsius. Below this temperature, the roots of the plant have more trouble taking up water and nutrients. Too high a temperature is not good either. That will kill the plants Tap water must be warmed up to 25 degrees C. Use a water thermometer to keep an eye on the water temperature. Warming the water is easy with the installation of a heating element in the nutrient tank. This equipment also comes from the aquarium world. Quality heating elements with thermostats are available for aquariums. For a 100 liter nutrient tank, you need a 100 Watt heating element; with a 200 liter tank, we recommend a 250 Watt element. Make sure the heating element is always kept under water; otherwise it will be destroyed. This means that you must never pump all the water out of the nutrient tank to the plants. When you want to take the heating element out of the water, always disconnect it first. Then, let it cool off for at least 15 minutes. Only then can you carefully take it out of the water. Any other way, you run the risk the element will crack. To prevent algae growth in the nutrient tank, it's important to add air to the water. We do that by means of an aquarium pump with an aerator attached. The aerator is connected to the pump, and placed at the bottom of the nutrient tank. The water in the tank becomes rich in oxygen by aeration, and is also kept in motion. This way, algae have much less chance to proliferate.
Guide to Watering Plants:
Indoor Plants - Watering
The main cause of death of potted plants is over-watering. Roots need both water and oxygen, and when surrounded by water, they cannot take up oxygen. These roots may rot and eventually the whole plant may die. The symptoms of over-watering and underwatering are similar. Both lead to poor root health, root decline and possibly death of the plant.
A common question from gardeners is "How often should I water my plants?" There is no pat answer to this question. The amount and frequency of watering depends on many factors, such as the plant species, its growth stage, its location, the type and size of its pot, soil mix characteristics and variable weather conditions.
There is a wide range of watering requirements for different species of plants. Plants with large or very thin leaves and those with fine surface roots usually require more frequent watering than succulent plants with fleshy leaves and stems that are able to store water. Some plants thrive under moist conditions while other plants grow well when kept drier.
Plants may slow in growth after a flush of new growth or a heavy flowering. During these periods and while it is dormant, a plant will need less water.
Water evaporates rapidly from the sides of a porous clay pot, which requires more frequent watering than nonporous, glazed or plastic pots. A large plant in a small pot needs water more often than a small plant in a large pot.
Different soil mixes require different watering schedules. Heavy, fine-textured potting media and those that contain a lot of peat moss hold more moisture than loose, porous mixtures of bark, sand and perlite.
A plant in a warm, dry, sunny location needs more frequent watering than one in a cool, low-light environment.
The rule-of-thumb is to water when necessary. The following methods may be used to determine when to water:
Touch the soil – The most accurate gauge is to water when the potting mixture feels dry to the touch. Stick your finger into the mix up to the first joint; if it is dry at your fingertip it needs water.
Tap the pot – When the potting mix in a clay pot begins to dry, it shrinks away from the sides of the pot. Rap the side of the pot with the knuckles or a stick. If the sound is dull, the soil is moist; if the sound is hollow, water is needed.
Estimate weight – As potting mixtures become dry, a definite loss in weight can be observed.
Judge soil color – Potting mixtures will change from a dark to lighter color as they dry.
There are a number of watering meters available to measure moisture in the soil, indicating whether water is needed. These products vary widely in accuracy. The readings can be influenced by factors other than soil moisture content. Fertilizer and soil type can affect the reading.
When watering is required, water thoroughly. Apply water until it runs out of the bottom of the pot. This washes out the excess salts, and it guarantees that the bottom two-thirds of the pot, which contains most of the roots, receives sufficient water. Don’t let the pot sit in the water that runs out. Empty the saucer.
Do not allow the soil to become excessively dry. If the salt level in the container is high, root damage may occur. If soil does become very dry and hard to rewet, use the double watering method. Water once and then again half an hour later; or place the pot in a sink or a bucket of water. Remove the pot when the soil surface is moist. Allow the pot to drain completely. If peat is allowed to dry completely, not only is it difficult to rewet, it also will not hold as much water as it could hold before it dried.
Do not water with hot or cold water. The water temperature should be between 62 and 72 °F.
Do not water plants with softened water because sodium and chloride will also be added to the soil mix, possibly causing plant damage.
Although wilting is often an indication of the need to water, it is not always so. Any injury to the root system decreases a plant’s ability to take up water, including root rot, which is caused by too much water. This inability to take up water will cause wilting, and under these conditions, watering may make the problem worse.
Excerpted from the South Carolina Master Gardener Training Manual, EC 678.
Last edited:
happy water grows happy plants 
good discussion thread...
