Deep Water Culture Res Temp


Hey there @MacGyverStoner @RobertBergman @latewood

wondering if its worth it to invest in a water heater. My rez drops down to 62 F at night. My rez is using about 15 gal and is not recirculating.


I have always been happy to have my res’ temps. in the 60’s.up into the 70’s. 62 is a bit low, but not dangerous. How warm does it get during light photo period?

MacG will have an exact temp, and perhaps a tighter res temp range.


I agree with Latewood, about 62F-71F is the safe range for DWC. As long as it doesn’t get colder than 61F you should be fine. You can get up to 78F in DWC with an almost over-board amount of aeration but it is easy to have low oxygen problems much above 72F, and much lower than 61F and cellular activity and nutrient absorption at the roots will be slowed, slowing growth.



yaa you right say


I use a chiller to cool my Rez because at 70 deg I was experiencing root rot. Lowering the temp in the Rez solved the root rot issue. I use a lower temp of 55 deg and my results have been amazing. My last grow produced huge full ripe buds on all plants and the roots stayed healthy and white.


If you could increase your dissolved oxygen at closer to 68*F you’d have even more amazing results. Root rot happens because of not enough dissolved oxygen in the water. You could increase aeration to get more O2 in the water.

It is a known fact that the cellular metabolism slows a lot below 61*F. But if it works for you, as they say, if it ain’t broke, don’t fix it.

If you gave me some more info, I might be able to figure out why you are getting root rot, or not having enough dissolved O2 in the water at slightly higher temperatures.

Are you supplementing your crop with CO2 also?



Hey Seebee, Just wondering about your DX… Do you or have you ever actually tested and confirmed the DO in your culture water when your roots are dying and decaying, actually confirming that low DO even at 70F is suffocating your roots or are you just guessing that low DO is the culprit that is killing your roots and inviting the fungal outbreak? If your roots are suffocating all the beneficial microbes are probably suffocating too.
Without minimal safe oxygenation death, decay and fungal infestation is imminent and you can count on an outbreak. I have read that some growers feel that 2 PPM DO Concentration is OK and will keep roots, microbial colonies healthy enough, that’s safe oxygenation and that should prevent fungal outbreaks, different people have original ideas about what’s safe oxygenation and when frank suffocation begins.