DWC water temps - too cold?

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Autotron

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I'm planning to try hydro for the first time on my next grow. I have everything necessary for a 5 gallon DWC with recirculating pump putting water directly on the seedling plug to get a head start in veg.

The temps in my grow space may be too low right now though. The air temp is about 52F in there. How cold is too cold for DWC water temp? I've seen elsewhere that temps below around 60-62F will stunt growth, with ideal temps being closer to 68F. Will be using a single AutoCOB, so I can't rely on heat from that to warm up space. Does anyone have experience with low water temps that they could share as well as any pointers?
 
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woody

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Ideal water temps for dwc are 18-20oc or 64-68f.
A little lower is no problem in my opinion- its when it goes over 68 that things can go wrong.
A little aqarium heater is cheap and easy to use where as a res chiller is expensive.

My only tips are buy a good ph and ppm pen and get either hydroguard or sm90.

Also i wouldnt bother with the top feeding.
Keep the water level 1 inch below bottom of net pots and the air pump bubbles enough water up for the stones to wick up to the rockwool.
Completely up to you though brother :thumbsup:
 

Mañ'O'Green

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Below 65°F will retard growth. 4 gallons of water is a big heat sink in a small tent if the water is 65°F the airspace won't be much warmer. I like my tent running at 78°F to 82°F. 70% H daytime 10 degrees cooler 55% for nightime. The reason it is recommended for your reservoir to run at 68°F is because water will retain the best saturation of oxygen there. I have run in the summer time with reservoir temperatures as high as 84°F without problems (be sure to run Botanicare Hydroguard). So running at 74° in the res should not be a problem.
 
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woody

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Running your res as low as 17oc or 62f will not retard growth in my first hand experience.
Maybe i picked it up wrong but my understanding is that the lower the water temperature the more dissolved oxygen it can hold?
Saying that i completely agree that 20oc or 78f is the ideal res temp
 
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Autotron

I used to smoke weed. I still do,but I used to too
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I saw cheap 8 watt submersible aquarium heaters on amazon for $10 a piece. They're supposed to bring a roughly 1.5 gallon betta tank up to 76-80F at room temperature, so one or two of these may be just what I need to get me in the sweet spot. I'm digging the low price and low wattage.
 

Henry

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I have heard that oxygen (DO) is a big deal too in a hydroponic canna-grow. All the Bro’s know that plenty air bubbles guarantees plenty D-oxygen. The Bro’s think that in order to have plenty dissolved oxygen DO, you got to have cold water, use water chillers and bubble plenty air in the water and that’s what it takes to insure plenty DO. At least that is a very popular opinion bases on internet DO chart predictions. My Bro sister proved that wrong with a DO test.

Questions: Do any of you dudes have any idea what the best DO range really is?

So what are the DO numbers, the DO concentration and the DO saturation numbers of the best oxygen range?

Have any of you ever actually tested the dissolved oxygen in your water or ever actually thought about testing the your DO?

My favorite Bro’s sister did actually tested her DO 1 time and discovered that her DO was only <2 PPM DO. Her DO chart predicted that her DO concentration would be 100% saturated @ 9 PPM DO in her cold, chilled water… the DO chart missed by 7 PPM DO.

She caught a dose of the root rot overnight and then caught a hefty dose of the Pythium fungi the next day. The 3rd day she pitched the mess because her apartment was stinking real bad.

What lesson did she learn? She learned she could not trust the DO chart, fungi are real and you better worry about Pythium, that’s what she learned.
 

Jimmy Joe James

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Dude just get hydroguard and forget worrying about rez temps. Day 18 of my grow and rez temps at 77f my roots couldnt be happier.

Also a drop of hydroguard in a spray bottle with water makes an excellent foliar spray innoculant
 

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Autotron

I used to smoke weed. I still do,but I used to too
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With the two mini 8 watt aquarium heaters, it brings the water temp to 68.5F in my 54F space. I'm sure the AutoCOB will add a degree or two. Is that still too cold to germinate and support a seedling to veg? I was planning on putting a glass dome over the top until it sprouts and sheds it's shell, so that I can add some heat via greenhouse effect and moisture. Temps in my space won't be rising for a total least a couple months.

Important to mention that these are the temps in a space that's pitch black at the moment, so I expect the temp to rise a bit once the light comes on.
 
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woody

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Water temps are fine. But 54f air temps are too low. Can you use a heater?
 
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