It is not that difficult to achieve a constant high temperature of, say, 250 degrees Celsius or a low temperature of 80-90 degrees Celsius. You can also achieve a constant low temperature for up to even 12 hours without adding new charcoal.
You control the temperature with the top ventilation disc and the bottom ventilation. To allow the temperature to rise slowly, start with the top and bottom ventilation that are only open for a small part. You can slowly open these a little further and further to allow the temperature to rise. The more oxygen, the higher the temperature.
Do you want to put out the fire? Then you close the top and bottom vents. It couldn't be easier! Note: Do not use water to extinguish the coals, this can damage the ceramic.
TIP: Always use a plate setter when slow cooking at a low temperature. Then don't let the grill get too hot. It does take hours to bring the temperature down. If you want the temperature to drop, slide the top and bottom vents closer.