11 1/4x23 1/4x1 Exact MERV 13 AC Furnace Filters 12 Pack refurbished-products Key features include:

Key features include:

Can increase to 2-3 teaspoons as above

High flow rate of 7 gallons per minute or 420 gallons per hour

keep your crops free from pests

These four products combine to form the backbone of HN's natural feeding schedule and can easily be expanded with more natural Humboldt Nutrients additives and products

11 1/4x23 1/4x1 Exact MERV 13 AC Furnace Filters 12 Pack refurbished-products Key features include:Nordic Pure MERV 13 Pleated AC Furnace Air Filters provide exceptional filtration for both home and commercial environments. Each time air passes through a Nordic Pure pleated furnace air filter, lint, dust, pollen, bacteria, pet dander, dust mites, mold spores, smoke particles, virus carriers, coughs and sneezes, smog, allergens and other contaminants are removed. MERV 13 furnace filters are comparable to HVAC filters with the rating of MPR 2200