Why do people recommend such low water temperatures for hydroponic root zones?

ScienceGrow

Member
I have no experience with hydroponics.

According to most of the information I have gathered, the ideal root zone temperature for cannabis is between 26-30 C, which is higher than word of mouth recommendations that I have seen for hydroponics, and is around 18-24 C. Certainly, high temperature impacts the oxygenation of the root zone, and I suspect that hydroponic growers are either afraid of increasing the water temperature or know for certain that it will negatively impact oxygenation in a way that is unacceptable.

I also suspect that warmer temperatures might lend itself to more algae issues, and keeping it below 20 C will reduce the probability of this becoming a problem.

Can someone enlighten me a bit more on this discrepancy?
 

ҖҗlegilizeitҗҖ

Well-Known Member
I have no experience with hydroponics.

According to most of the information I have gathered, the ideal root zone temperature for cannabis is between 26-30 C, which is higher than word of mouth recommendations that I have seen for hydroponics, and is around 18-24 C. Certainly, high temperature impacts the oxygenation of the root zone, and I suspect that hydroponic growers are either afraid of increasing the water temperature or know for certain that it will negatively impact oxygenation in a way that is unacceptable.

I also suspect that warmer temperatures might lend itself to more algae issues, and keeping it below 20 C will reduce the probability of this becoming a problem.

Can someone enlighten me a bit more on this discrepancy?
I wpuld like to see your source on the 30c becuase I call BS
optimal is 20°C
The lower the temp, the higher the dissolved oxygen level. To a point where the plants speed of growth slows, the lower the better.
People bring it down to 16c with no adverse effect.
At 30c though, you would have issue saturating your water in oxygen. This would encourage root rot, also it makes products like Hydroguard and UC root much less effective.

I could of assumed you don't have much real world experience on this without having been told.
 

Failmore

Well-Known Member
We keep are nutrient solutions cold in hydro to combat bacterial growth. Lower temps help keep the bad guys away.

Lower temp water contains more dissolved oxygen.

That is all there is to it.

I can't keep my water cold so I run sterile.

Not being able to keep the res cold does not mean you can't go hydro. Just gotta do it different.
 

ҖҗlegilizeitҗҖ

Well-Known Member
"When you’re growing cannabis and providing the water your plants’ roots intake, your plants benefit most when you deliver water that’s 67-68°F. (20c) This temperature has been shown to protect roots from heat stress, aid in maximal uptake of nutrients elements, and is the temperature at which water oxygenation is very high."

 

ScienceGrow

Member
I wpuld like to see your source on the 30c becuase I call BS
optimal is 20°C
The lower the temp, the higher the dissolved oxygen level. To a point where the plants speed of growth slows, the lower the better.
People bring it down to 16c with no adverse effect.
At 30c though, you would have issue saturating your water in oxygen. This would encourage root rot, also it makes products like Hydroguard and UC root much less effective.

I could of assumed you don't have much real world experience on this without having been told.
Researchers at Utah State University found this to be the best root zone temperature for cannabis. But this is probably in a substrate, and I think you are correct about dissolved oxygen. This is also probably why substrates are superior to hydroponics as a medium for cannabis.
 

ScienceGrow

Member
This is a lecture from Utah State University on different cannabis parameters, and they definitely say 26-30 C is the root zone temperature. Water is a different story, though.
 

grass_fish

Active Member
In Hydro if you want to grow at higher temps you can with Nano bubblers. The price for these things is in the 5 k area. If you use a oxygen concentrator it will need to be on alot with a RDWC. The best way to use these systems is with a media based flood and drain system so you dont eat your expensive oxygen concentrator too fast. For a cheaper cost in a Rdwc you can use a few tricks to bring it into the 24ish range, although can be risky if you are the type to walk away for a few days. Higher temps mean more time and diligence, everything is moving fast.

When I run my grow at 80F it flies. Like a weeks worth of normal hydro growth in three days. Zero pyth issues. Not ideal for small grows but great for larger grows.
 
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