Am I doing something wrong? My shop vac is a 15 gal? 5.0 HP. I put drywall dust bags in and after the bag gets MAYBE 1/4 full, the bags tear and allow the dust to blow out the exhaust. The bag that came with it lasted until it was about 2/3rds full, but the bags I bought at Home Depot tear almost right away. Are there better bags?