This growbox is in the attic. The girls just entered to flowering stage so I turned on the exhaust ventilator. This caused that the temperature dropped drastically, especially during the dark hours. (The intake air temp was only 6-10C degrees)
Magnesium deficiency signs appeared on the leaves and I read about the problem. These symptoms appeared because of the roots are cold, the soil temp dropped below 11C degrees.
The tent is in the attic so I cut the ceiling and now the girls gets warm air from the house 😁
I mix always 5 litres fertilizer and now I put one tablespoon epsom salt to the water. (1tsp/5l)