Hi, If you put your hand over the return with the filter running and a clean cartridge installed you will feel a strong flow of water. Over the course of a few days or a week you will notice this flow slowing down. That's when you clean the filter.

For me it's a once a week thing. Clean filter, run cleaner for a few hours while I lay on a raft drinking beer, clean filter again. Good to go for another week.

Something like that. Just get a good feel for that return flow. That's your best pressure gauge.

Dennis