soultouch
- 52
- 18
Hi, 9 years late to this conversation, but i spotted at least one or more errors in the FatMan discussion about plant roots only taking up DO Dissolved oxygen and not gaseous o2. First off Air contains about 20% Oxygen, This is 20,000 ppm not 2000 ppm oxygen. [ % times 10,000 = ppm.] Moreover, plant roots obviously take up gaseous oxygen. In any soil / soiless system the air space between particles is where plants roots get their oxygen [Cells in the leaves get plenty of oxygen from photosynthesis, but cells in the roots often need to get oxygen from the environment to stay alive. Even though roots are buried, they can absorb oxygen from the small air spaces in soil.Nov 18, 2004
Plants need oxygen - UCSB Science Line]
These roots are absorbing gaseous O2. Aeroponic, fog systems provide water and oxygen this way. Fatman is correct that most large bubbles simply find path of least resistance and then pop at the surface. Smaller bubbles would be better or at least more efficient, and at most one can only temporarily super saturate the water. How long is temporary, don't know but i would assume roots would benefit. DO meters only measure a max of 20 ppm, tough i have seen some for sale that measure 50ppm. so no matter how much air or even pure oxygen, one will not get a reading above 20ppm with a meter that only measures 20 ppm. An oxygen generator concentrator that pumps 95-99 % pure oxygen would work, but pretty sure the energy economics will not justify the upfront expense or the running expense. I own several O2 concentrators. LOUD as hell and 120v * 6 Amps = 720 Watts for the output of 5 liters per minute of oxygen. So a cheap air pump that minute oxygen vs an air pump that outputs 25 liters per minute would give an equal amount of oxygen probably for far less energy cost, along with nitrogen and other components of air.
It is true that under regular circumstances fresh water is often saturated with only 9 to 12 ppm depending on temperature which is why large growers growing exclusively hydro chill their reservoir water to keep temp around 68% be cause pythium and other root rot diseases explode above those temps because there is too little dissolved oxygen in the water. Fatman is correct that simple pumping of recirculating water or use of eductors or venturi to mix ambent air into water will usually max out DO in reservoir water and should be adequate in elevating oxygen in the root zone. If one finds a way to temporarily pressurize the water in a compressed air chamber one could also super saurate the oxygen level, i think this is HENRYS LAW or Boyles law of pressure and gas
but until i experiment i would not be able to say how long the extra oxygen dissolved would be available. I would theorize that one could invent a combo foold and drain that cycled so frequently that it would serve as a RDWC system only guaranteed to have huge amounts of oxygen between the draining cycle and reflooding with newly mixed and oxygented water. Care would need to be taken not to fry the roots but imagine on could keep the roots dry for mere minutes. I am sure someone out there has tried this already and worked out the timing. If so , please share, it will save me a lot of time
Also, i just acuired a fairly high end DO meter and think i have a way to measure super saturated water oxygen levels, i think i can dilute with BOILED Distilled water. Read somewher that boiled water has almost zero ppm oxygen. I will bil some and repost the numbers, but if true i could dilute by a factor of 10 to 1 distilled boiled water to freshly sampled air stone, air diffuser, eductor, venturi, sprayed water or vigorously mixed water and be able to detect and measure any supersaturation beyond 20 ppm. Let us say one can for even 10 minutes hike the DO level to 50 ppm, one could devise experiments to track differences in growth and biomass. i do know there is some research that too much air can precipitate some nutrients but cannot recall specifically
Plants need oxygen - UCSB Science Line]
These roots are absorbing gaseous O2. Aeroponic, fog systems provide water and oxygen this way. Fatman is correct that most large bubbles simply find path of least resistance and then pop at the surface. Smaller bubbles would be better or at least more efficient, and at most one can only temporarily super saturate the water. How long is temporary, don't know but i would assume roots would benefit. DO meters only measure a max of 20 ppm, tough i have seen some for sale that measure 50ppm. so no matter how much air or even pure oxygen, one will not get a reading above 20ppm with a meter that only measures 20 ppm. An oxygen generator concentrator that pumps 95-99 % pure oxygen would work, but pretty sure the energy economics will not justify the upfront expense or the running expense. I own several O2 concentrators. LOUD as hell and 120v * 6 Amps = 720 Watts for the output of 5 liters per minute of oxygen. So a cheap air pump that minute oxygen vs an air pump that outputs 25 liters per minute would give an equal amount of oxygen probably for far less energy cost, along with nitrogen and other components of air.
It is true that under regular circumstances fresh water is often saturated with only 9 to 12 ppm depending on temperature which is why large growers growing exclusively hydro chill their reservoir water to keep temp around 68% be cause pythium and other root rot diseases explode above those temps because there is too little dissolved oxygen in the water. Fatman is correct that simple pumping of recirculating water or use of eductors or venturi to mix ambent air into water will usually max out DO in reservoir water and should be adequate in elevating oxygen in the root zone. If one finds a way to temporarily pressurize the water in a compressed air chamber one could also super saurate the oxygen level, i think this is HENRYS LAW or Boyles law of pressure and gas
but until i experiment i would not be able to say how long the extra oxygen dissolved would be available. I would theorize that one could invent a combo foold and drain that cycled so frequently that it would serve as a RDWC system only guaranteed to have huge amounts of oxygen between the draining cycle and reflooding with newly mixed and oxygented water. Care would need to be taken not to fry the roots but imagine on could keep the roots dry for mere minutes. I am sure someone out there has tried this already and worked out the timing. If so , please share, it will save me a lot of time
Also, i just acuired a fairly high end DO meter and think i have a way to measure super saturated water oxygen levels, i think i can dilute with BOILED Distilled water. Read somewher that boiled water has almost zero ppm oxygen. I will bil some and repost the numbers, but if true i could dilute by a factor of 10 to 1 distilled boiled water to freshly sampled air stone, air diffuser, eductor, venturi, sprayed water or vigorously mixed water and be able to detect and measure any supersaturation beyond 20 ppm. Let us say one can for even 10 minutes hike the DO level to 50 ppm, one could devise experiments to track differences in growth and biomass. i do know there is some research that too much air can precipitate some nutrients but cannot recall specifically
