Below is taken from Neptune’ Systems Guide, more specifically IQ Level Settings:
IQ-Level is a form of calibration that allows you to configure the pump’s minimum and maximum speeds to be optimal for your aquarium. Using IQ-Level is entirely optional but is highly recommended.
In the next few paragraphs, we will discuss IQ-Level as it should be done for a common aquarium setup in which the COR is used as a return pump. Other COR uses, such as closed loop applications, will require different criteria be used for IQ-Level.
Ideally, the pump’s maximum speed will be calibrated so that 100% speed corresponds to that speed which moves the perfect amount of water for the tank’s overflow drain(s), without exceeding the capacity of the overflow or pumping insufficient volume of water to maintain a constant full siphon drain. This is important to do, as properly setting the maximum speed of the pumps ensures that the output of the pump will not exceed the capacity of the overflow and drain system, even if the COR slider on the Dashboard is set to manual ON.
Ideally, the COR’s minimum speed will be set with IQ-Level so that when the pump is running at 1%, the pump does not slow so much that the water in the return piping drains out backwards. The perfect minimum speed is that speed which just holds the water column full and in a quiescent state, and does not actually cause water to be pumped. You would then program to COR to run at that minimum speed during feeding times and in other situations when no water movement is desired.
