Trouble Controlling Nutrient Reservoir Temperature
I'm having an unexpected problem with rising temperatures in
my nutrient reservoir. I say its unexpected because the
temperature in the grow room is 63 degrees F. The grow
room is in the back corner of the basement and I've
closed the HVAC vents and shut the door.
When I first mixed the 30 gallons of nutrients, the water
temp was about 52 degrees. Its been a cold winter. They
were drifting up, but I thought it was just trying to
equalize to the room temperature. It hit 63 and has kept
Its now around 76 degrees and I'm trying to lower it with
blue ice packs.
Question - what is the maximum safe temperature the
nutrient solution can be at?
I'm trying to understand where the heat may be coming from.
For instance. Does the air pump add heat to the nutrients?
I've taken readings of the temperature and it can climb
a 1/2 a degree in an hour without any nutrient pumping.
Then, during a nutrient pumping, the temperature of 30
gallons of nutrient can increase 3 degrees. I just had
my 6PM feeding and the temperature went from 68.9 to
72.0. The absolute temperature of the thermometer may
be off, but the change in temperature should be accurate.
I feed twice per day at 6am and 6pm. I understand why the
return nutrients would be warmer during the evening feeding.
The grow chamber has been between 76 and 79 degrees for
12 hours. But, when I measured the temperature of the
return nutrients, they were at 84 degrees, higher than the
ambient temperature of the grow chamber. I thought about the
black tubing acting as a solar shower. The grow
light shining on the 1/2 ID black tubing could heat the
water in the tubing higher than the ambient temperature.
So, I wrapped them in the reflective foil I used on the
walls of the grow chamber to reflect the light away. Did
At midnight, when the grow lights shut off for six hours,
I run an exhaust fan until the temperature in the chamber
drops to 68 degrees. The fan will keep coming on all night
to keep the temps below 68 degrees. The low temperatures
recorded each day is 66 degrees, so that is working. The
nutrient reserve in the bottom of the Dutch buckets should
cool to 66 during the six hours of night and the grow
media should also cool so that the first feeding of the
day at 6am right when the lights come on should not pick
up any heat from the grow chamber. But, the temp of my
reservoir will increase by 3 degrees.
Does the submersible pump add much heat when its
Does anyone have any ideas where the additional heat is