21x21x1 MERV 14 Plus Carbon AC Furnace Filters 6 Pack Master Controller Standard application: Use 4-8 ml

Standard application: Use 4-8 ml per gallon of water once per week or with every feeding

There is no Restricted Entry Interval (REI)

Their tunnels are lined with earth worm castings and allow oxygen to reach plant roots

Diameter: 250mm

21x21x1 MERV 14 Plus Carbon AC Furnace Filters 6 Pack Master Controller Standard application: Use 4-8 mlNordic Pure Custom MERV 14 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