16x18x1 MERV 13 Plus Carbon AC Furnace Filters 6 Pack timers-and-instruments 002 pH pH Calibration Automatic

002 pH pH Calibration Automatic

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pH Down™

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View readings from your PC or mobile device so you'll know when to adjust your nutrient solution to the optimal range

16x18x1 MERV 13 Plus Carbon AC Furnace Filters 6 Pack timers-and-instruments 002 pH pH Calibration AutomaticNordic Pure Custom MERV 13 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