Root & Water Temperatures in Coco

doob · Sep 24, 2015

So winter is around the corner, and this means some of us will be worrying about cold conditions very soon. I grow in an external building, so ambient temps have a big effect on my groom.

I have built a box which my pots sit in. This will then have a heater in it keeping the pots a nice temperature. I also have a tank heater to go in the reservoir.

So my question to you is, what would you say the optimum temperature for the roots/medium is and what temperature the reservoir should be at. I am thinking of setting both up at 20-21degC (68-70degF)

And lastly, what is the lowest temperature i should let the canopy drop to, if i have the roots at the optimum temp?

Thanks

jewcebox · Sep 24, 2015

anything over 70 in the res will have algae grow i believe

Snow Crash · Sep 24, 2015

I like my roots between 60f and 68f (~16c to 20c).

You want your canopy temperature to stay in a narrow range. Don't let your low temperatures drop more than 10f (5c) below the daytime temperatures for best results.

Your reservoir should remain cool to improve the dissolved oxygen capacity. I also keep this between 60f and 68f (16c to 20c) like my root system.

doob · Sep 25, 2015

Thanks for the replies. That is interesting looking at that graph, much appreciated. 16degC - 20degC it is, I can set the tank heater to 16degC and monitor the temperature with a probe i have. I will have to do some testing with the heating when it is all put together this weekend.

I will aim to keep the red box >16degC 24/7. The yellow area will drop when it is lights off obviously, i will have to see what sort of temperatures i am getting and go from there I think

Pumpkin · Sep 25, 2015

Your tank heater set at 20C should do the trick. The box seems unnecessary. Your lights should be enough to heat up the room. Feed just before lights on (1 hour-30 mins) and get them warm before the growing starts. At lights off I would not bother heating the roots, the plants are not doing a lot of growing at night anyway. What's your outside temps? How cold are we talking?

I've never had issues, but my nights only really hit -4C, if you are colder than that perhaps more extreme measures may come into play, but I'd still be trying to increase lights on room temperature rather than heating the roots only.

Don't worry about algae. Algae needs light so won't be in your res anyway. If it's growing on the top of your coco, don't give a shit either

doob · Sep 25, 2015

My set up is in a single skin external building, intake temperature will be low soon. Probably average 5-10degC through winter, perhaps some cold spells at zero. Ideally i would insulate the tent and warm the intake I know, but where it is it cannot be done successfully, I would be chucking away money trying to heat it up.. I grow autos because of this issue, so lights off will be short, I can even leave them on 24/7 all though I have never tried that past week 4. I use blumats so they will be constantly dripping when needed

stoned40yrs · Sep 25, 2015

I don't have sealed or heated rooms and deal with Alaska cold air all winter. I can tell you this for sure- when the root zones in coco get into the 40s and 50s you will get nute lockouts in the plants. Single best tip if you grow in colder rooms is to elevate the plants off the floor. Cold air sinks. Milk crates work good so we are talking at least 12-14" off the floor. I try to get 60 lights off and res temp of 60 for the blumats. Lights on I grow with 70-75 at top of the canopy. Some days my rooms are sucking in air that is way the hell below zero, lots of fun growing in winter here :biggrin:

doob · Sep 25, 2015

Yes i bet you have a right battle over there! Interested how you keep temps so high on lights off though. The box I have made will be insulated and sealed, the pots will slip in and I will stick a tube heater in there. That should keep them nice and toasty downstairs. Mine are raised on insulation etc before the tent, then they will be off the floor so it should keep them nice i hope

jewcebox · Sep 25, 2015

will you be draining runoff out of boxes? heat and humidity + darkness= mold

Bush Dr · Sep 25, 2015

Air temperature is not as important as humidity

I've had one of my best crops ever with the temperature of the intake fan reading-10C, as long as you keep the root zone in the 18-22C you'll be fine, just make sure they can drain properly ......the buds were so hard they ripped the pins out of a grinder and very potent too

stoned40yrs · Sep 25, 2015

doob said:
Yes i bet you have a right battle over there! Interested how you keep temps so high on lights off though. The box I have made will be insulated and sealed, the pots will slip in and I will stick a tube heater in there. That should keep them nice and toasty downstairs. Mine are raised on insulation etc before the tent, then they will be off the floor so it should keep them nice i hope

I close off my air intakes during lights off and stick a small heater in the rooms also. This keeps it around 60. I guarantee if the root zone gets in the 40s or low 50s you'll get lockouts. I learned the hard way. :tiphat:

doob · Sep 28, 2015

jewcebox said:
will you be draining runoff out of boxes? heat and humidity + darkness= mold

They will be elevated, with an individual tray beneath each pot. Once the blumats are set up, they produce very little if any run off. So as long as i keep an eye on it and keep it clean will be fine (i hope haha)

Bush Dr said:
Air temperature is not as important as humidity

I've had one of my best crops ever with the temperature of the intake fan reading-10C, as long as you keep the root zone in the 18-22C you'll be fine, just make sure they can drain properly ......the buds were so hard they ripped the pins out of a grinder and very potent too

Nice. This is my thinking, focus first keeping the roots/medium optimum temperature. And go from there. The box will be sealed so i wont be extracting all my heat out constantly

stoned40yrs said:
I close off my air intakes during lights off and stick a small heater in the rooms also. This keeps it around 60. I guarantee if the root zone gets in the 40s or low 50s you'll get lockouts. I learned the hard way.

Yeah i dont plan on finding out what temps i get lock out :biggrin:

I cant close intake where it is and I am not there all the time.

I will update this thread with how I am getting on, thanks for all the replies

BAYSIK401 · Sep 28, 2015

Just my opinion..... Keep it all around 68....

I use big smart pots lights on 72, lights off 66, RH always around 55-62%...

Water temp before being applied is at 67-72, very nice..

doob · Nov 12, 2015

Updates woooo.

So far so good with my boxing in idea, the box is made out of 22mm MDF, which is strong enough to support the 4x plants in the cutouts. I have insulated the box with 20mm foam, and added a 45w tube heater inside. And it is keeping it at 24-25degC 24/7. It is literally perfect, so I am very happy so far.

These SS KillerKush went mad after I got it set up, a couple have completely out grown my space hehe

Lots of testing left to do, but this basically means I can stop growing Autos and get some Regs going very soon now I dont need to use the light to heat the space

p0opstlnksal0t · Jan 31, 2018

Anyone have any idea if having reservoir feed water temps in the mid 50's will cause lockout? Im showing Mag deficiencies but trying to chase it down is being a real pita. my reservoir water temps are usually around 52-57 degrees when we have real cold nights 10-20 degrees.

Midwest Toker · Jan 31, 2018

I start noticing deficiencies when my floor thermos drop to 65 degrees. https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/determining-soil-temperature.htm

p0opstlnksal0t · Jan 31, 2018

Midwest Toker said:
I start noticing deficiencies when my floor thermos drop to 65 degrees. https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/determining-soil-temperature.htm

My Coco/bucket temps are a constant 70-72 degrees but my feed water is usually 55 degrees or so.

cocktail frank · Jan 31, 2018

anything under 60? degrees i believe slows absorbtion down to a crawl. the plant has no uptake at those temps.

Midwest Toker · Jan 31, 2018

By your avatar, we will be watching the same show on Saturday at 4pm.

Midwest Toker · Jan 31, 2018

p0opstlnksal0t said:
My Coco/bucket temps are a constant 70-72 degrees but my feed water is usually 55 degrees or so.

You should avoid large swings in your root temps.

Root & Water Temperatures in Coco

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