20x20x4 (3 5/8) Furnace Air Filters MERV 10 Pleated Plus Carbon 2 Pack complete-systems Position the unit in the

Position the unit in the grow space with adequate clearance on all sides for airflow (minimum 12 inches recommended)

seaweed feeds plants

Now OMRI Listed and WSDA certified for use in organic production

available exclusively from Hydrofarm

including injector and drip systems

20x20x4 (3 5/8) Furnace Air Filters MERV 10 Pleated Plus Carbon 2 Pack complete-systems Position the unit in theImportant Note: Almost ALL furnace filters have a different "actual size" than the nominal size printed on the air conditioner filter. It's best if you measure your air filter for the EXACT size and compare it to our "Actual Size" and then you can be sure your A C air filter fits! With the 4" and 5" air filters there is a wider variance between the nominal and actual size depending on the manufacturer. If you are replacing a 4 3 8 depth 20x20x4 filter