PERFECT Res Temp without approximation?

giantcola

giantcola

Well-Known Member
Hey Growers! I wanted to ask a simple question trying to figure out what the perfect temperature for water in hydro would be, within maybe 2 F.

(I got a new tool that allows me to regulate it without approximation)

Let's say i have a DWC - RDWC system, i use h202 to sterilize the water and i can follow the VPD chart exactly, room temperature being a couple degrees (5 - 6 F)warmer than res.

Right now i'm aiming for 66 F, but i'm wondering if maybe the plants can benefit from a bit higher or lower temp.

Do you think that at lower temps (63-65) may the growth be stunted even with the increased oxygen levels?
Maybe some nutes won't be as available?


On the other side, do you think that increasing the res temp to around 68-70 F would boost the growth speed? Hoping to not get any root problems even with H202 thought..

I know this might be overthinking :mrgreen::bigjoint:

But let me know what you think as you got experience to share!!

Good Sunday People!
 
voodoosdaddy

voodoosdaddy

Well-Known Member
68 degrees. Lower temps won't increase oxygen levels but will slow growth. You don't want to really go above about 74-75 as the water won't hold as much oxygen but it will lead to more algae growth. But yeah...68 is perfect.
 
thenasty1

thenasty1

Well-Known Member
higher res temp=faster plant metabolism=less dissolved oxygen content
lower res temp=slower metabolism=higher dissolved oxygen content
i like 72f. as long as you stay on top of your application of sterilizing agents (or bennies for that matter) and your flow rate is appropriate for the volume of your system, you will have nothing to fear from waterborne pathogens. this is the happy medium between dissolved oxygen availability and metabolic potential in my opinion.
 
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Psylo

Member
Although it goes against convention I disagree with the above. Search online and you will find recommended water temps in hydro horticulture range a LOT higher than the 20C/68F that is typically suggested here. Here’s my comments on the key points:

1. Higher res temps will give faster growth. What that translates into for a grow I have no reliable data, e.g. does it mean my 16 weeks can finish in 15 weeks? No idea, but warmer will be faster.
2. Lower res temps inhibit the baddies that produce root rot - true I guess but that problem can be solved with more certainty by running sterile, I use bleach and have no issues. My tap water has 1ppm chlorine and I add bleach to around 3ppm every 3-5 days. I have no experience with running beneficial organics but maybe that can work also.
3. Lower res temps can hold more dissolved oxygen - also true but it’s a very marginal reduction in DO as temps go up, even up to 30C/86F. Also with good bubbles in DWC whatever is used by the plant is immediately replaced. I think this (DO levels) is a completely irrelevant point.

In my personal experience root rot is the key enemy in DWC and the best way I have found to negate that is to run sterile with bleach (H202 may also work). With that under control res temps become a non-issue.
 
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bluegill

Well-Known Member
I keep mine dialed in at about 72F. My reso temp is usually whatever temp the ambient house temp is - just takes some time for the reso to catch up when it changes. I dose enzymes and haven't had a problem with established plants. Clones and seeds are monitored a little more closely.
 
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bigbadbillybob

Member
fish tank steriliser will kill pathogens so no need for h202.
Why not just use chillers? they maintain the perfect temp.
As for running the res hotter (so that pathogens and bacteria will be able to thrive), then killing said bacteria, pathogens and the microbial life with bleach, its counter productive, and ridiculous imho.
Bleach will cause Na buildup in the res, and will require more frequent res changes, but i suppose if you are changing out regularly it wont matter. Pool shock is the correct answer if you cant afford a chiller, as it uses the Ca+ ion instead of Na+, so much less toxicity.
And thats without mentioning the lower DO.at higher temps, but hey, if you're all happy adding toxins to your res, crack on :)
 
Horselover fat

Horselover fat

Well-Known Member
I don't think there are studies on cannabis. Leafy greens grow more in warm water. Like 27c warm, but that may not translate to cannabis.
 
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sativuuh

Member
My chiller is set to 65, but it lets it drift to 67 and the second it hits 68 it chills it all back down. It's usually reading about 66 on the monitors. That 65-69 is good, stay consistently over 70 and you start to have some battles to fight and need to use some Hydroguard or z7 or both in there to help prevent issues. Keep it nice and cool and those are not needed, nor is adding and bleach or anything to your water like was said above. Also make sure you don't get any light leaks into your res.
 
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EarthAngel

Member
Psylo said:
In my personal experience root rot is the key enemy in DWC and the best way I have found to negate that is to run sterile with bleach (H202 may also work). With that under control res temps become a non-issue.
Click to expand...
You may want to be careful running bleach as a preventative, it does irreparable damage to roots that they cannot adapt to like they can h202.
This smart guy can tell you better than I can:
 
rkymtnman

rkymtnman

Well-Known Member
EarthAngel said:
you didn't even watch the video did you? it's not "chlorine" that hurts the roots, it's hypochlorous acid which is what is produced from bleach in solution.
Click to expand...
i dont' watch videos when i've used pool shock for years and have real world experience. chlorine is safe to drink at less than 5ppms.
 
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