Maybe I am still not understanding things correctly. I am trying to understand how I get 10psi on my gauge right of the pump and the reading at 9ft water depth.

Is the Vertex not designed to be used as a single disk diffuser? Or as a single disk is it meant to be used with a lower pressure compressor?

At 9ft depth, .5psi per foot I should be running about 4.5psi at the pump. However with the single Vertex I get over 10psi at the pump and setting off my pressure relief valve. However if I pull the diffuser up and swap out to my old stone diffuser I am about 5psi or just over.