Hi all
New here, also new to growing, so please be gentle.
I have been reading up on DWC for white a while and I'm terribly puzzled with the whole DO and temperatures.
Just about any site will quote you that perfect DWC temperatures are above 16°C (62F), because plants don't really like cold that much, and below 20°C (68F), because apparently dissolved oxygen drops too low. There is almost always an extra warning that temperatures above 21°C will just about suffocate any plant, since dissolved oxygen drops "very fast".
So I did a google search
. It appears that solubility of oxygen is quite well studied, since the ocean people use for the science thingy. It is also quite handy, that ocean temperatures ranges from 0°C to 35-ish °C, and vary in salt concentration as well.
So here is a simple chart one can find on google:
Here is similar info in table form:
If I'm reading this right, there is no magical "dip" of DO above 21°C. Not even a hiccup. The difference in DO between 20°C (68F) and 25°C (77F) is very very small (0.6 ppm).
Furthermore, them more dissolved salts in the water, the bigger the drop in DO. This drop seems much larger then temperature one. So if you use more nutes and lots of additives, your DO will suffer accordingly.
Another google hit states that 4ppm DO is about minimum for many plants to survive, with 7-10ppm being "normally maintained" with extra note that higher DO does not have any advantages for plants. So 25°C should be just fine as far as DO goes. (for those non-metric...ly inclined, 1 mg/L equals 1 ppm). Even if you go to 35°C (and not cook your plants), you would still have more than 4ppm of DO as long as your nutes are below 35-ish ‰.
So my question would be: is there an explanation, preferably a scientific one, why would DO at 21°C or above be deadly (suffocating) for DWC? Let's disregard other problems caused by high temperatures (root rot, etc.) and stick to DO vs Temp.
I'm not trying to stir shit up or be a smart ass since my growing experience is very limited to say the least, but I really like to (over)plan all my project and this one just bugs me. Are the temperatures quoted everywhere a part of folklore that just get repeated over and over again, or is there any substance behind those claims?
New here, also new to growing, so please be gentle.
I have been reading up on DWC for white a while and I'm terribly puzzled with the whole DO and temperatures.
Just about any site will quote you that perfect DWC temperatures are above 16°C (62F), because plants don't really like cold that much, and below 20°C (68F), because apparently dissolved oxygen drops too low. There is almost always an extra warning that temperatures above 21°C will just about suffocate any plant, since dissolved oxygen drops "very fast".
So I did a google search
. It appears that solubility of oxygen is quite well studied, since the ocean people use for the science thingy. It is also quite handy, that ocean temperatures ranges from 0°C to 35-ish °C, and vary in salt concentration as well.So here is a simple chart one can find on google:
Here is similar info in table form:
If I'm reading this right, there is no magical "dip" of DO above 21°C. Not even a hiccup. The difference in DO between 20°C (68F) and 25°C (77F) is very very small (0.6 ppm).
Furthermore, them more dissolved salts in the water, the bigger the drop in DO. This drop seems much larger then temperature one. So if you use more nutes and lots of additives, your DO will suffer accordingly.
Another google hit states that 4ppm DO is about minimum for many plants to survive, with 7-10ppm being "normally maintained" with extra note that higher DO does not have any advantages for plants. So 25°C should be just fine as far as DO goes. (for those non-metric...ly inclined, 1 mg/L equals 1 ppm). Even if you go to 35°C (and not cook your plants), you would still have more than 4ppm of DO as long as your nutes are below 35-ish ‰.
So my question would be: is there an explanation, preferably a scientific one, why would DO at 21°C or above be deadly (suffocating) for DWC? Let's disregard other problems caused by high temperatures (root rot, etc.) and stick to DO vs Temp.
I'm not trying to stir shit up or be a smart ass since my growing experience is very limited to say the least, but I really like to (over)plan all my project and this one just bugs me. Are the temperatures quoted everywhere a part of folklore that just get repeated over and over again, or is there any substance behind those claims?
