Final Reprise
DM did someone say 75F and you're done? Actually temps sustained over 78F and things are likely to tank, but that's only if other co-factors are out of balance. It's this synergy of imbalance that can and will tip the scales against you, so just make zero mistakes and you'll be fine.
BM...you refer to rooting which more often then not requires a heat mat with low temps to maintain between 74-78F for establishing
primordial roots, which can then blossom into feeder roots. This recommendation is for grow mediums like rockwool, peat, coco, perlite.....not water.
Use an aero cloner or bubble cloner and you'll experience delayed rooting at the a fore mentioned temps. This is an easy misconception so I can see where you might be confused. If you'd like more info on optimum aero cloning temps contact
ez clone and I'm sure they'll get you dialed in.
As for nutrient manufacturers recommending tepid water....this is primarily to aid in further solubilizing the mineral nutrient to aid in it's dilution. And tepid water applied to soilless mediums housing ben. biology can stimulate plant roots.....
in a soilless media, not water as a substrate.
Fact of the matter is the rules we've learned as gardeners change when water becomes the primary grow medium. Referencing rules that apply to soil, coco and the like isn't that unusual, unless you've grown in water.
No doubt plants can live in water conditions in the mid 70's - low 80's. But it's at these temps that plant roots are far more likely to be over whelmed by anerobic bacteria which thrive in warmer, lower DO conditions. I've even seen plant roots grow in water conditions close to 100F, but I'd never recommend this to anyone with a crop as valuable as MMJ.
Bottom line....DM's got what sounds to be a pretty cool room which should keep his root temps reasonable. This coupled with his obvious skills as a gardener should keep him out of trouble and hopefully provide a banner harvest.
As far as this endless information stream for water culture....unfortunately this doesn't yet exist which is why your misunderstanding is so common. Carbon media based (rockwool, peat, coco, perlite) hydroponics has been pretty well mapped out, but water culture is still a bit of a black art. It's only recently that more professional applications are bringing about a real interest in the facts...more so than the opinion.
I'd like to close with an opinion of mine...cannabis grown in warmer water temps tends to be larfy, and lacks the oil content of what you see grown in sub 70F temps.
This is an opinion and only an opinion.
