21x23_1/2x1 MERV 12 Plus Carbon AC Furnace Filters 6 Pack nutrients This is the 1

This is the 1

especially with inert media and when using reverse osmosis (RO) water

These awesome kits are made with Gorilla's high standards and easily snap into place horizontally on the frame of your Gorilla Grow Tent

when installed on water systems

Seeing is believing

21x23_1/2x1 MERV 12 Plus Carbon AC Furnace Filters 6 Pack nutrients This is the 1Nordic Pure Custom MERV 12 Plus Carbon air filters are made based on the actual measurements so be sure to measure your current filter to get the EXACT dimensions before ordering. As with all Nordic Pure filters, the effective life of your filter depends on the environment in which you live. We recommend changing 1 and 2 filters every 30 90 days. Our 4, 5 and 6 inch thick filters could last up to 6 months. EXACT MEASUREMENT: Furnace and air condition