CONTROLLING THE ENVIRONMENT
How Important Is Water Quality In Hydroponics...
Water quality is an important determinative factor in hydroponics cultivation. Water is the basic ‘carrier’ in hydroponics as it dissolves and transports nutrients for plants. However, water also dissolves a lot of impurities that can be harmful to plants. These impurities cannot be easily detected visually, and it is all too easy to be misled into making wrong assumptions about the purity of water from the clarity of a sample.
Fortunately, solutions to water quality problems, in the majority of cases, are simple and do not involve complicated methods and techniques. Even small growers can use some simple and proven techniques to effectively solve their water quality problems. The types of water quality problems that growers will likely face depends on the water source from which they draw water for their hydroponics garden. Poor water quality can lead to a number of plant growth problems including stunted growth, mineral toxicity or deficiency symptoms, build up of unwanted elements in plant tissue, bacterial contamination, etc. Though causes of poor water quality are numerous and varied some of the more frequently encountered of these are
1. Chlorination
Chlorination is the most extensively adopted measure to control bacterial contamination of water supplies in cities, towns and other urban centers. In hydroponics cultivation, the use of chlorine by growers to kill pathogens in their water has caused problems in a number of instances. It was found that this happened due high levels of active chlorine in the water used to make nutrient solution. Chlorinated water sources need to be aerated in a ‘holding tank’ for 48-72 hours (depending on the initial concentration), with good ventilation during which time the active chlorine levels fall to below 1ppm, a safe level for the plant’s root systems. Chlorine in nutrient solution water is known to cause damage to several crops especially to sensitive crops such as lettuce, salad greens, strawberries and others.
2. Unwanted minerals
Water being an excellent solvent dissolves a large number of substances including minerals. While some of these are beneficial, others like sodium, for instance, are quite harmful. Plants do not require sodium and sodium chloride if present in water can cause problems even in small quantities. Sodium can be very harmful especially in re-circulating systems. Plants differ widely in their sensitivity to sodium; some plants like tomatoes can tolerate much higher levels of sodium than other plants such as lettuce. Sodium needs to be kept below 80 ppm for healthy growth of most plants, but below 30 ppm for plants such as lettuce.
Magnesium, calcium, potassium, sulfur, nitrates and trace elements such as boron, copper, manganese and zinc may be present in water from various water sources. This can be taken care of in most cases by suitably adjusting the nutrient formulas to factor in the presence of these elements thus preventing accumulation and toxicities in the water supply. The presence of trace elements can be more troublesome and may require demineralization and dilution of the water source with pure water supply when using in nutrient solutions.
3. Microbial or pathogen contamination
Water from sources such as wells, ponds streams etc. often contains organisms that should be removed before the water can be used in nutrient formulations. The most common of these ‘pathogens’ is Pythium, which can attack plants when present in sufficient spore concentration. Growers have successfully used chlorination as a line of defense against these pathogens, but it requires that the chlorinated water be held for a few days to allow to the concentration of chlorine to drop to levels tolerable to plants. Hydrogen Peroxide can also be used to kill pathogens such as Fusarium wilt and Pythium in water and nutrient solutions.
4. Iron and Iron bacteria
Iron in the form of iron hydroxide is usually present in water from ground water sources near areas with deposits of iron sand or iron ores. The iron hydroxide in water, though not directly harmful to plants presents a number of problems due to the blockages it causes in various components of the system. These blockages if not removed, from an ideal medium for growth of iron bacteria, which consume a variety of elements that are provided for plant growth in hydroponics systems. Iron hydroxide removal methods include aeration and settling or flocculation with different agents. Iron bacteria can be removed by sterilization of the water or nutrient solution.
5. Hard water sources
Water is termed ‘hard’ when it contains substantial amounts dissolved calcium bicarbonate and other elements. When in contact with pipes and equipment the calcium bicarbonate changes to insoluble calcium carbonate also known as lime scale. Hard water forms scale in irrigation pipes, heating elements and pumps causing severe blockages. Computerized water conditioner units similar to the ones used in domestic water supplies can be used to eliminate scaling problems in hydroponics systems.
6. Herbicides
Cases of herbicide contamination of ground water sources and even municipal water supplies are not unknown. Herbicide contamination manifests as damage to sensitive crops such as tomatoes. Activated carbon filtration can help reduce damage but care must be taken to replace the carbon often enough to enable it to retain its efficiency.
WHY WATER TEMPERATURE IS SO IMPORTANT
Postby
Cyco Nigel » Thu Sep 08, 2016 9:55 am
WHY WATER TEMPERATURE IS IMPORTANT
In my opinion for optimum results your water temperature should hover around 19 - 22 degrees Celcius (67 - 72 fahrenheit)a little variance above or below that isnt the end of the world but keeping it in that zone as much as you can would be your aim.
When your water (root) temp is high you start to experience negative results. Pathogens which are disease causing bacterium, virus and other microorganisms that like and thrive in warm water, then they begin to outnumber the good ones.
Bacteria and fungi thrive in warm water as well. Also when water temp's are to high your plant will suffer
from heat stress. Also the higher the water temperature, the less of an ability the water
itself has to hold onto dissolved oxygen molecules. The plant needs to absorb these oxygen
molecules for plant growth, as well not to suffocate. Especially important in water culture
systems where the roots are submerged in the nutrient solution 24/7.
Using a air pump with the air stone in your nutrient solution can help in two ways.
First it replaces the oxygen molecules that the plants absorb. The bigger the plant
the more oxygen your plant will absorb, you can never get to much oxygen to the root systems.
Second is that pathogens are reduced in the oxygen rich water, but beneficial microorganisms thrive.
Having lower water temperature's isn't as bad for your plant but it will stunt and slow your
plants growth. Once the temp gets around 10°C (50°F) it will be noticeable, and around 4.5°C (40°F )the
plants growth gets really slow. If you find that your water temperature's are getting low you
can get those aquarium heaters to warm your water up. If using one try to keep it from touching
any plastic in your tank, cause it could actually melt a hole in your tank.
