Saltwater pool with Hayward system and chlorine generating cell. Pool is running fine, no issues. Turned the spa on tonight to heat it up and it ran fine for about 10 minutes and then would shut off. Display said "Check System-No flow - Filter". I could turn the filter back on and it would run fine again for another 10 minutes and then shut off. I haven't a clue what is going on. Any hints? I had a tech out for another problem last week and he reset all of my settings. Any comments appreciated!