Reconditioned (257 from $ 5.93) Whirlpool Charcoal Pre-Filter (Large) for use with AP45030K and AP51030K air purifiers. Whirlpool Charcoal Pre-Filter (Large, model 8171434K 4-pack) for use with AP45030K and AP51030K air purifiers. the filter reduces VOCs and odors while trapping larger particles to pre-clean the air and help preserve your HEPA filter.Choosing the Right Air Purifier Based on Reviews One of the most reliable product reviews website for consumer is Home Air Guides. They collect reviews, analyze those reviews results and recommend the best products to buy to their readers. The top five air purifiers they recommend are the Blueair 503, IQAir New Edition HealthPro Plus, Whirlpool AP51030K Whispure, Honeywell 50250-S and Filtrete Ultimate Allergen 1900. These air purifiers range in price from one hundred dollars to nine hundred and fifty dollars. Price is actually another way of determining what kind of a product you’re getting when buying an air purifier.