18x18x2 Furnace Air Filters MERV 8 Pleated Plus Carbon 12 Pack Grow Strong Sunshine #4 Natural & Organic

Sunshine #4 Natural & Organic is recommended where high air capacity and fast drainage are needed

or 4 GPH torturous path

Perlite and Dolomite Limestone (pH adjuster)

This leads to lack of feeding

Sonoma Gold Grow and Bloom are all-purpose

18x18x2 Furnace Air Filters MERV 8 Pleated Plus Carbon 12 Pack Grow Strong Sunshine #4 Natural & OrganicNordic Pure 18x18x2 MERV 8 Plus Carbon air filters are made of a dual material where the MERV rated material has been fused together with a carbon layer. This results in less flow restriction and 33% more surface area for cleaner smelling air. It will help eliminate unwanted odors as well as trap most airborne dust and particulate matter for fresh, clean air. Odorous gases and vapors (VOC) are attracted to and held by the activated carbon material