Vacuuming pool

[BrettvanDanny]

I have a problem new pool owner 1 year I have a Hayward navigator pro , every time I hook my vacuum up my vac works for anywhere from 1-5 mins and then my psi climbs to 20 from 10 psi (normal operating psi) I lose suction and my vacuum stops but I don’t lose prime, otherwise the pool runs flawlessly I’ve checked hoses , I have a regulator to ensure proper flow to vacuum, my pump seal o ring is brand new, my sand filter is brand new , the pool works great otherwise any suggestions on where my problem may be?