This started a bit last year after I bought a new cartridge filter. The check flow error would come on, I would check the union basket. It would be caked with debris. I’d clean it and good as new for a few weeks. It started happening more frequently after the new cartridge but this year it’s almost happening daily. I’d check the union basket and it’s just covered in debris. This didn’t seem to happen as much with my old cartridge. Could it be just a lousy filter cartridge? I have cleaned it 4 times already this season with a comb water pic as well as soaked it in dishwasher detergent. I don’t see any holes or anything in it. It’s a pletco advantage so it’s not like it’s generic or anything.