It is clear you just repeat what is written all these years on cannabis forums.
OK, let me enlighten you as you refuse to give answers.
To much oxygen or to little oxygen causes root stunting
Again too much oxygen and cold temperatures on roots will stunt growth
Nonsense.
Roots don't know if there is too little or too much DO in the water. Roots absorb O2 molecules and are not aware if this molecule is coming from a lot of DO or just a little. Of course when there is too little DO, then at a certain moment there are no molecules that can be absorbed. But this can happen in both cold water as in warm water.
It is true that cold water can stunt growth, but there is no relation between how much O2 is available per se.
Oxygen uptake is going to differ on any plant??? Big roots/big plant =more oxygen uptake that's kind of a silly question lol
No, it is not. Only for those who don't know science.
Roots of most plants that can be grown in greenhouses and such (also cannabis) are using around 200 mg of O2 per hour per kilo of roots.
Your res is gonna hold as much DO as you put in. Tapers off around 14mg/l that's about the max
Again, you don't understand it.
Although by itself it is true that water of a certain temperature can contain a maximum amount of DO, it is also a fact that the moment your roots absorb some of that DO, the oxygen in the rez is replenished. Simply by atmospheric pressure. So the amount of DO in a rez is endless.
It is a common mistake that people think that if you have a rez of 100 liter with a temperature of 68 °F , that it can hold only 100 x 9.2 mg of DO = 920 mg of DO.
Totally wrong. It can never
exceed the amount of 920 mg at any moment. But that is not the same.
If there is 920 mg in your rez and your roots absorb 100 mg of this, then the not so educated people think that there is only 820 mg left.
"And that is why cold water is better"
But the scientific facts show us that after the roots absorb the DO, the DO level will be around 920 in the rez again. Simply by the never ending supply of O2 through atmospheric pressure.
So even if your roots are in warmer water, it makes no difference.
At 77 ° F it is 8.4 mg's and that is plenty of DO.
At 86 °F it is still 7.6 mg's. So when your rez is a 100 liter the amount of DO can never exceed 760 mg. But when the roots absorb 100 or 200 mg, a moment later there will be 760 mg of DO in your rez again.
Of course when the temperatures become really high, or if you have too much roots in a DWC that is too small, or if you have a tote that is deep and with a small surface, it can lead to problems. Then there is simply not enough time to 'refill' the amount of DO.
Again 62-68°F is the perfect ideal zone. Over 72 DO dips to low.
Wrong. 62 is near 'too low'. There are not many cultivated plants on earth that do well with this temperature.
The 'ideal zone' is much wider as your 6 degrees. It is for most cultivated plants - including cannabis - between 66 and 80.
For lettuce and tomatoes it is around 77 degrees (according to Cornell University). For spinach it is 72.
Why would the laws of biology and physics not apply to cannabis? For sure every plant has it's own 'ideal temperature' and with cannabis even every strain. But the members of the bro-science brotherhood come up with their own facts.
As long as you supply your roots with enough DO, then the higher the temperature, the better your plants will do. Don't overdo it of course.
Although some strains of cannabis grows perfectly well in soil of 84 degrees. And the basic structure of a plant on DNA level does not certainly change when it is grown in hydro.
It is a scientific fact that metabolism works better at higher temperatures. (That is also the reason why some root rots do better at higher temperatures)
As explained before, at 72 DO will not dip too low. As long as you 'refill' with fresh DO.
Phytophthora occurs at lower temps and Pythium occur at higher temps.
Here you are right. The ideal temperature for Pythium for example is 68 degrees. But Pythium can be heavily triggered by changing EC's as well.
The mantra of cannabis growers 'low temperature prevent root rot' is just to simplistic.
There is not 1 cause for root rot. There are several kind of root rots.
Even commercial growers sometimes don't know what causes root rot in their systems. And many of them look the same for the naked eye.
What they do is have the fungus or rot analyzed. DNA analysis. So when they know what disease they have, they can change the growing circumstances to prevent that specific disease; Lowering the temperature or making it higher, a more stable EC, making sure their feeding water is already on a higher temperature, etc.