I am changing out the sand in my filter. My pool requires 325 lbs of silica sand, meaning it will only require 162.5 lbs of zeolite sand. Bags of zeolite come in 25 or 50 lb bags. Can I use 150lbs for my filter or do I need to spend the extra money on another bag to reach 162lbs, or should I pour the rest of that last bag in and have 175 lbs. Thanks.