DIY Deep Water Culture, The Recirculating Oxygen System http://www.bestseedbank.com/diy-deep-water-culture-the-recirculating-oxygen-system/#comment-26234
A few things jump out about this article: This is about a recirculating aeration system, not a recirculating oxygen system.
The author says, “Roots are able to meet their oxygen requirements from either the 02 in the air or through dissolved 02 in the nutrient solution. A dissolved oxygen content of above 4 to 5 mg/L (4 to 5 ppm) is required to sustain respiration and enable nutrient conversion. Extremely rapid root growth is recorded in water with a dissolved
oxygen concentration of above 9 mg/L (9 ppm).” [this is air – this is not oxygen the element O2]
Then says, “An air pump and manifold Silent diaphragm air pumps are the best option; they are very low wattage
, often between 15 and 40 watts for 1200 to 5000 litres per hour: Many of them are also designed to be operated continuously.” [oxygen system deliver pure oxygen, they do not deliver air]
The author drops the hammer and says,
“Pythium typically thrives in oxygen deficient and anaerobic water. !” [preventing low oxygenation in nutrient solution is less discouraging and aggravating and far better than treating the full blown fungal disease after it has established and killed root cells and microbes… like preventing athletes foot fungi by simply wearing clean socks and keeping your feet dry.]
The verbiage Oxygenation or mechanical aeration is a slippery slope at best, a common misnomer, misconception – let’s be specific for a change, the real difference between oxygenation and aeration is like daylight and dark.
Most people, growers and writers consider oxygen and air to be the same gas so this sounds like if you pump plenty of air surely there is will be plenty of oxygen for the plant eco system and the microbe eco system too… It’s logical that more plants, bigger plants and more microbes require more oxygen, Right?
If you ever had an infestation of Pythium fungi be assured that this pathogen is a ubiquitous opportunist and thrives because the environment you created was hypoxic (low insufficient oxygen). Eliminate your hypoxia and Pythium cannot thrive. Prevention is better than the cure.
This article is about the positive effects of sufficient aeration with mechanical aeration. Aerating is basically pumping plenty of air with an electric air pump. Pure air is not pure oxygen. The limiting factor of air is the low fractional concentration of oxygen in the air. Air is 80% nitrogen. The point is providing plenty of oxygen gas, not providing plenty of nitrogen gas.
Everyone says oxygen is really important. How do you insure plenty of oxygen… most folks hope a lot, depend on air (aeration) and are programed to chill the water with an electric chiller, maintain nutrient temp between 65F – 68F. and blow more air in the water always hoping there might be enough dissolved O2 in the water. They think about the possibility root rot every day.
Few growers have ever actually measured their solution DO Saturation with a DO meter considering the meter too costly and not very important. They always relying on Standard DO saturation charts based on air, fresh water, water temp, salinity and barometric pressure. Most have no concept of DO Supersaturation for 80 F water (DO Supersaturation 150% at the head waters and DO saturation at the tail waters… the difference being a loss of 50% Saturation consumed by plants, microbes and off-gassing throughout 1 flow cycle through the RDWC system.
If the microbe colony is small and the plants are small, of course a minimal amount of oxygen is required and mechanical aeration is usually sufficient. But, if the plants and root zone is large and the microbe colony is large, well, to be healthy they will require more oxygen (oxygen is the key word, do not be confused with the word air, “air” means a mixture of many gases).
It seems like a logical person would consider providing more oxygen if the 2 eco systems are hypoxic and need more oxygen. That sounds like the most logical most economical thing to do to me if you really want to insure minimal safe oxygenation continuously. Yet most people never consider this and minimal safe continuous oxygen is really not very important. – What you see is what it is.
Thanks for posting that url.
J