Most Commonly Asked Filtration Question Series The risks of not using vent filters on holding and mixing tanks are real. And costly. Unfortunately, we usually hear from a company after they've experienced serious issues because they did not install vent filters. So, this article is written for those not yet using vent filters on their tanks. It will address the most common issues/questions we're asked on this topic with the hope of sparing you a process headache you don't need. Many processes require the use of tanks for holding ingredients to be added into the process, mixing of ingredients, or to hold the final product pending final filtration and filling. During the course of normal operations these tanks will be filled and emptied many times.