When do I need to make a new custom calibrated medium for my Bluelab Pulse?

When your current custom calibrated medium no longer gives you a 90%-100% moisture reading when at maximum water holding capacity (after plant has been watered to the point of draining and has been left to free drain for an hour), it is time to create a new custom calibrated medium.

This change could be because you are using a custom calibrated media from a different plant/media type, the plant is in a bigger pot, the plant is larger (more roots) or the media is more compressed than when you first made your custom calibrated medium.