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Minimum temp for DWC? External heater?

phattybudz

phattybudz

Member
I never thought I would be worried about my temperature being too low! But it's getting to be winter and temps are coming down to 62 during the colder part of the night... Considering getting an external heater to keep it right at perfect temp.

62 is probably too cold right? At least for optimal growth...

Any recommendations on an external heater for a ~30 gallon rez with 1/10 ecoplus chiller?

Thanks!
 
fatigues

fatigues

Active member
Veteran
There is a wide divergence of opinion on the proper temp for DWC.

Some will say this is WAY too cold. Without putting too fine a point on it? Those people are wrong (and probably live in warmer climates).

There are commercial growers who deploy chillers to try and KEEP their Rez between 58 and 62 degrees. (Most growers in BC aim for this temp.)

If your plants are okay at with a rez at 62 (and I'm sure they are)- leave well enough alone.

Remember that roots are made for soil. Soil, at about 3 feet below the surface (which is how deep the roots of a medium sized plant grown outdoors ALWAYS reaches) has a temp which is in the low 60s.

Below 4 to 5 feet or so, soil temp is ALWAYS in the mid-50s due to thermal inertia of our planet (unless you happen to live above the tree line, that is). But in moderate to even equatorial climates? The soil of our planet is always cool.

And that depth is where roots from large cannabis plants will routinely grow into. They survive that temperature nicely. They'll survive 62 without trouble, too. I promise.

All by way of saying: chillax. If the air temps are 60ish? Not so good. You want those at about 66-70 at night and about 76 in the day (if you can).

But the rez? You're fine at those temps.
 
G

guambomb813

Member
fatigues said:
There is a wide divergence of opinion on the proper temp for DWC.

Some will say this is WAY too cold. Without putting too fine a point on it? Those people are wrong (and probably live in warmer climates).

There are commercial growers who deploy chillers to try and KEEP their Rez between 58 and 62 degrees. (Most growers in BC aim for this temp.)

If your plants are okay at with a rez at 62 (and I'm sure they are)- leave well enough alone.

Remember that roots are made for soil. Soil, at about 3 feet below the surface (which is how deep the roots of a medium sized plant grown outdoors ALWAYS reaches) has a temp which is in the low 60s.

Below 4 to 5 feet or so, soil temp is ALWAYS in the mid-50s due to thermal inertia of our planet (unless you happen to live above the tree line, that is). But in moderate to even equatorial climates? The soil of our planet is always cool.

And that depth is where roots from large cannabis plants will routinely grow into. They survive that temperature nicely. They'll survive 62 without trouble, too. I promise.

All by way of saying: chillax. If the air temps are 60ish? Not so good. You want those at about 66-70 at night and about 76 in the day (if you can).

But the rez? You're fine at those temps.
Click to expand...


I've ran dwc for couple years along with ebb n flow in other room and I do not live in a warm climate, so it's a little bold of you to say that I am wrong in knowing that those temps have never been optimal for me.

Although those temps never showed a damaging result, my growth was not "optimal". The logs I keep proved this. Just with lowering my res temps down from 72 to 65 my nutrient and h20 uptake per day was lowered along with the amount of co2 that was disbursed in the room per day.

Root zone temperatures are very important for the best uptake, working hand in hand with air temps. If your root temps must stay low then to achieve best growth you would need to have higher then normal air temps.
I would imagine that the commercial growers you speak of also keep a higher air temperatures?
Viscosity of the water/nutrient mixture also rises with lower temperatures (more resistance) and lowers with higher temps. Higher viscosity makes it harder for the small hair vessels to uptake.

I know each of us have different factors in our grows so these can lead to differed results but just thought i'd share my experience.

-.-
 
D

DHF

I gotta say this with no disrespect Fatigues ........Growin indoors with artificial environment and the roots growin in water is nothing like growin in dirt outdoors in natural surroundings where soil temps never dip below 55 degrees....

For the record , dissolved oxygen is able to accumulate more ppm`s at lower bottom container temps in the 61-65 degree range , but everytime my rez or bottom container temps got below 65 degrees growth slowed.......guaranteed......

I ran krusty buckets for over 8 yrs that recirculated 24/7 and my dialed results for explosive root AND foliage/flower development was 69-ish with not enough difference in DO levels to matter more than juice temps........Had a big-ass aqualogic drop in "probe" chiller that kept shit to the degree at all times.......

But Fatigues is right in that lower temps keep nasties and root born pathogens at bay thus why the greenhouses he speaks of would sacrifice faster growth for not worrying about higher rez temps and fear of potential crop failure......all about trade-offs for the greater good.......

Good luck.....DHF....:ying:.....
 
G

guambomb813

Member
DHF whats up! always good to hear your input.
Question to you: Which DO meters have you used/prefer? I have one by Sper Scientific but don't know anybody personally with another type to compare accuracy to -.- Thanks.
 
D

DHF

Never had a DO meter GB , but did my homework and listened to what the pro`s like Krusty and Heathie were using and had determined with their meters and research , then went on blind faith many many yrs ago.....

Research online is what let me know about dissolved oxygen at "saturation " rate was 61 degrees , and krusty taught that 65-69 was the comfort zone without getting into the 70`s and potential root pathogens.........

We found out SM-90 @ 5ml per gal was an excellent deterrent to root rot if container temps got past comfort zones , and had other qualities such as rootzone bug control as well.......

We flushed and sterilized everything once a week , then started over again anyways , with no chance for nasties to breed.......wasted buncha juice but grew some monsters......

Good luck...DHF....:ying:....
 
phattybudz

phattybudz

Member
Hmmmm....

Guess I will go see how much heaters are at my local shop...

No recommendations on type/brand for 30 gal rez? thanks guys..
 
T

TheBioMaster

Member
Comparing roots in the soil outside and roots grown indoor in a DWC is pretty crazy...not even apple and oranges I dont think......
 
phattybudz

phattybudz

Member
FWIW...

Ended up grabbing a 100 watt heater at the local store today...

Everything will stay at 68 F now... optimal.

Booyah.
 
D

DHF

Wayta handle shit PB.......Getchas some SM-90 for added insurance and you`ll be good ta go.......

Peace.....DHF......:ying:.....
 
!!!

!!!

Now in technicolor
Veteran
The textbook minimum is 65F but 62F is OK. Below 60F and plant growth may begin to slow down considerably.

My res dips as low as 58F but I run ebb/flow so it's not much of an issue for me.
 
G

guambomb813

Member
!!! said:
The textbook minimum is 65F but 62F is OK. Below 60F and plant growth may begin to slow down considerably.

My res dips as low as 58F but I run ebb/flow so it's not much of an issue for me.
Click to expand...


What are your air temps? Interesting I'm running ebb n flow buckets and I saw growth slowing when I had temps at 65. My air temps were at 72-75. I never saw any lack of chlorophyll or abnormal leaf senescence but the growth rate seemed to slow and my nute/h20 uptake went down! weird!

-.-
 
D

DHF

There is no "textbook" minimum concerning dissolved oxygen concentrations !!! , only results from dialing conditions once problems were overcome in the process of finding said rootzone and upper ambient room temp conditions for optimal results with dialed conditions below after the fact for increased yields............

I only told what worked for MANY folks once info was known , not just what worked for me and nobody else.......

As I said above.....Explosive growth above and below the rootzones resulted in the 69-ish degree area being optimal from my results using a totally recirculating "fast" hydro setup ......

FWIW....DHF......
 
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