16_1/2x21_5/8x1 Exact MERV 8 Plus Carbon AC Furnace Filters 6 Pack X Nutrients Grow Spray 1 Gal Most importantly

Most importantly

Neutral pH - Won't affect solution stability

bathrooms and attics

PHB4015 Ballast features:

Autopilot's digital CO2 controller measures the carbon dioxide level in the grow room and automatically turns on and off the CO2 device to accurately keep the carbon dioxide PPM at the desired level

16_1/2x21_5/8x1 Exact MERV 8 Plus Carbon AC Furnace Filters 6 Pack X Nutrients Grow Spray 1 Gal Most importantlyNordic Pure Custom MERV 8 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