its strange man.. weed will grow.. they say it wont after it hits 90 or something but i grew in an apartment bathroom for years and if i forgot to open my grow tent, (home made) it would get well up over 100.. never died
81 is high if your trying to keep your temps perfect.. but 81 will do if thats all you can get.. if you can cool it off a bit then great but if not.. whatever..i wouldnt worry about it 2 much..
oh .. also.. make sure you put a fan in there blowing on the plants.. you want the air in the room moving all around at all times.. this will cool the plants that are rite under the lights a lil bit and will bring fresh co2 to the plants
Hey GG, the perfect temp for both the root area and plant is 74-76F.
In that range, compensating temps can be used to arrive at the perfect temps.
You happen to have hit directly on the correct temps.
75F minus 68F equals 7 degrees.
81F minus 75F equals 6 degrees.
What this means is that you are actually only one degree off of the perfect temperature for your plant area. The lower reservoir temp compensates for the difference.
This only holds true for about a ten degree spread. You can't put your plants at 150F and the water at zero and have those temps work. That's a real exaggeration, but it shows the reality of the explanation.
Hi Bleek, what it is, is weed will stop *growing* at about 90F. It won't die, but it will go dormant and just sit there....and sit there....and sit there.
The plant processes virtually come to a stop. Some strains will tolerate higher temps and some will tolerate lower temps. It depends entirely on the strain of weed and how its grown. Root zone temps are very, very important and are directly related to the temps the plant will tolerate above the roots.