Greetings to all. Pool is the Intex 18x52. Just installed the Hayward CC15093S Full Flow 150 sq. ft cartridge with 1.5 hp motor. Plumbed with 1.5 pvc. Started it up and all seems good, I think. Sucking water. Pumping water as advertised. My question is this. Manual says max operating pressure is 30psi. May gauge is reading 9 psi. is that kosher? All seems fine. Just don't know what to judge it by.