Thanks for that Bob. I've come to the conclusion that wet and dry cycles are probaly the safest and easiest option, although I haven't found too much scientific information to suggest that measured dosage is more beneficial. I'd thought I'd post this because I found it interesting and its for anyone else who wants to know.

Plants, obviously as a by product of photosynthesis produce oxygen so that they have relatively easy access to oxygen during the daylight cycle. The roots on the other hand have a much harder time to utilise enough oxygen for their requirements. This results in restricting root respiration, which in turn slows photosynthesis, which in turn reduces the growth of the plant. Consequently, the happiness and the potential of the plant are very dependant uopn the roots securing enough oxygen. Plants are only able to grow as well as the roots allow it ; yeild can be directly measured in proportion to the root growth. Warm water holds directly less oxygen than the cold water, however, very cold water can be detrimental to the plants, effectively, shocking the root system until the water warms up enough for the plants to get over this shock. The colder and fresher the water, the more oxygen content ; the warmer, the less. Approximatly 0.0014% of dissolved oxygen can be found in very cold, fresh water. Approximately 0.0008% of dissolved oxygen can be found in fresh water at room temperature and water at room temperature is exactly how the plants like it. Heating your water too much can be very detrimental to your plants potential.

Oxygen obtained via the roots directly from the nutrient solutin only makes up 1% of the plants needs. So oxygen supplied via the nutrient solution is only a minor source supplied to the roots. Aerating the nutrient solution will help, however, this mainly serves to kill off any pathogens, basically keeping the nutrient fresher for longer. So you can see that allowing the plants some dry time will server to get more air to the roots. Even in aerophonics, which delivers a highly oxygenated solution directly to the rootball, it is essential to give plants dry time (at night for example) to allow air to reach the root system. Another tequnique is to add H202 to the reservoir, which again , due to its extra oxygen atom, increases the dissolved oxygen in the reservoir. However, when H202 is diluted, it becomes unstable and soon breaks down and dissolves completely into the reservoir, so it normally will only oxygenate the reservoir for a few hours. Also, when H202 is regularly administered to the reservoir, it keeps the nutrient solution fresher for longer. However, overdoing H202 can be very detrimental to the plant's roots. In high doses, it attacks many usable food chains that the plant will be deprived of.


Highly oxygenated root systems benefit from another very important fact. Oxygen manipulates and effects the electrical charge found in water and for that fact, nutrients. This changes in electrical charges allows roots to uptake water and nutrients with a lot less energy compared to non-oxygenated root systems, so clearly roots benefit from as much oxygen as you can provide them. Properly aerated solutions will absorb up to 0.0008% oxygen and hold it for up to 24 hours.

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