What Germ Guardian makes
Germ Guardian is a brand of Guardian Technologies. Its listings on Amazon US fall into four groups, and that's how this page is laid out:
- Air purifiers: towers, tabletop units and larger room units
- Replacement filters: lettered HEPA-type filters, carbon pre-filters and UV-C bulbs
- Humidifiers: cool-mist and warm-and-cool units, sold under the PureGuardian name
- Humidifier parts: demineralization cartridges for the PureGuardian humidifiers
The table above shows every live Germ Guardian listing in our data, checked weekly. A dash in the table means neither the maker nor the listing states that spec.
The brand names on Amazon can be confusing. Listings say GermGuardian, PureGuardian, and sometimes Guardian Technologies GermGuardian on the same humidifier. They're one company, and this page treats them as one brand.
Germ Guardian air purifier lineup
The purifier listings share a pattern. Most describe a HEPA-type main filter with a carbon pre-filter in front, an optional UV-C light, and a room figure in square feet. Most also state CARB certification. None of the purifier listings in our data states a CADR or a decibel level.
That's where my one opinion on this page comes in. Avoid any purifier that makes ozone on purpose, and look for CARB certification or an ozone-free statement on the listing before you buy. The EPA's guide to air cleaners says ozone is a lung irritant, and it names UV lights without adequate lamp coatings as one possible source. Germ Guardian purifiers use UV-C lamps, so the certification is the thing to check. Where a Germ Guardian listing states CARB or Zero Ozone Verified, the table says so. Where it doesn't, the table shows a dash, and I'd check CARB's list before buying.
The AC4825 family
The AC4825 is a 22-inch tower and the model people search for most by name. It has its own page: the Germ Guardian AC4825. That page covers the gray AC4825E, the white AC4825W, the two-packs and the AC4825EMJ bundle, plus Filter B, the carbon pre-filters and the UV-C bulb that fit it.
The short version: the AC4825E listing gives two room figures, 153 square feet every 12.5 minutes and 743 square feet every hour, and states CARB certification, ETL certification and Zero Ozone Verified.
Other 22-inch towers
Two more towers in our data share the AC4825's size and its 743-square-foot listed figure:
- AC4820: the listing describes an H13 HEPA filter and states CARB certification
- AC4880B: a black 22-inch tower; the listing states CARB certification, Zero Ozone Verified and a UV-C light
Both appear on the Filter B listings as compatible models, so they take the same main filter as the AC4825. If you already own one of these and want a second unit, matching the filter saves you a shelf in the closet.
Larger towers and room units
For bigger rooms, there are larger listings:
- AC5000E: a 28-inch tower by the listing, with a listed 915 square feet, UV-C and odor reduction; it states CARB certification and Zero Ozone Verified, and takes Filter C
- AC5900WCA: listed for rooms up to 1,760 square feet, with a True HEPA filter by the listing, UV-C, CARB certification and Zero Ozone Verified; it takes Filter J
There's also a Germ Guardian large-room listing in our data without a model number in its title. It states a 743-square-foot figure, UV-C and CARB certification. Read the model on that listing before you buy filters for it.
The EPA's air cleaner guide says to size a purifier to the room, and to go up a size for ceilings higher than 8 feet. A square-foot number with no CADR tells you less than it looks like. The AHAM Verifide directory lists certified room air cleaners with their CADRs, and it's worth a look before buying any model whose listing doesn't state one.
Tabletop and smaller units
- AC4100: the listing describes a True HEPA filter, a UV-C light with a photocatalytic layer, and a room of up to 375 square feet in one hour; it takes Filter E
- AC3200: a 21-inch unit the listing calls AirSafe+ XL, with a 360-degree filter, a listed 348 square feet, True HEPA by the listing, UV-C and CARB certification; it takes Filter O
These suit a desk, a nightstand corner or a small bedroom. Smaller units move less air, so plan them for the room you're in, not the house.
Germ Guardian filters, by letter
This is the part of the lineup people search for most after the purifiers themselves. Germ Guardian names its replacement filters by letter, and the letter on the box has to match the unit. Here's what the filter listings in our data say:
- Filter B (FLT4825): AC4825E, AC4825W, AC4820, AC4880, AC4900CA and others in that family; some listings add carbon pre-filters or a UV-C bulb
- Filter B with Pet Pure (FLT4850PT): the Filter B size with a treatment the listing calls Pet Pure
- Filter C (FLT5000, FLT5250PT): AC5000E, AC5250PT, AC5300B, AC5350B and others
- Filter E (FLT4100): AC4100, AC4150P, AC4150BL and others
- Filter J (FLT5900): AC5900WCA
- Filter K (FLT9400): AC9400W and AC9600W, a 360-degree filter by the listing
- Filter L, M, O and V: the AC4200; the AC4700 series; the AC3200 and related models; and the AC3000 series, in that order
The carbon pre-filter 4-pack, FLT22CB4, lists the AC4825, AC4900, AC4300 and others. Its listing recommends replacing the carbon layer every 2 to 3 months, depending on the room.
Other brands sell filters labeled as compatible with Germ Guardian units. Our data doesn't compare them. Whatever you buy, match the letter and the model numbers to the data label on your purifier, and make sure it seats in the frame. Air that goes around a filter isn't filtered.
The EPA says to replace filters on the maker's schedule, and sooner if they look heavily soiled, because a dirty, overloaded filter doesn't work well.
When to change them
Every April, the pine pollen comes off the trees on the far bank of our pond and turns the porch screens yellow. The pond goes green-gold for a week. That's the weekend I change the furnace filter and write the date on the notepad inside the coat closet. I've done it so long that Ana uses the pollen to remind me, not the other way around.
The point isn't the pollen. It's that a filter change happens when something reminds you. Pick a date, write it down, and let the notepad do the remembering. For a Germ Guardian purifier, the reminder light on the unit and the schedule in the manual are your notepad.
UV-C bulbs
The LB4000 replacement bulb listing names the AC4825, AC4900, AC5000 series, AC5900 and several others. It says the bulb needs replacing every 10 to 12 months, depending on use and environment. On many Germ Guardian units the UV-C light is optional. If you leave it off, the bulb isn't a regular cost.
This site doesn't claim the UV-C light does anything for anyone's health. The listings make their own claims, and the certification is what I'd check.
PureGuardian humidifiers
Germ Guardian's humidifiers are sold under the PureGuardian name, though some listings also say GermGuardian. The ones in our data are ultrasonic, and they come in two kinds.
Cool-mist units. These range from small personal units to tanks of about a gallon and a half:
- H910BL: a small unit with a listed 0.21-gallon tank, 210 square feet and auto shut-off
- H940AR and H955W: half-gallon tanks; the H955W also lists a humidistat and top fill
- H965AR: a 1-gallon tank and a listed 70-hour runtime
- H997W: a 1.6-gallon tank, a listed 90-hour runtime, a humidistat and top fill
- H3200WAR: a 1.5-gallon tank, a listed 100-hour runtime, a humidistat and auto shut-off
Warm-and-cool units. The H3250WCA and H5665B list both warm and cool mist with 1.5-gallon tanks. The H5665B lists a humidistat, top fill and a stated 35 dB.
The warm setting heats the water. The EPA's humidifier page warns that steam and boiling water may cause burns and says to keep steam units out of children's reach. If the unit goes in a child's room, use the cool setting or pick a cool-only unit.
The EPA also says ultrasonic units are very efficient at spreading tap-water minerals into the air as white dust, and that distillation is the most effective way to remove minerals from water. Use the water type the manual calls for, and clean the tank as the manual says. The EPA's general guidance for portable units is fresh water daily and a cleaning every third day.
Ana's ruling on parts: the cartridge number goes on a strip of tape on the tank, because the box is the first thing anybody throws out. She labels the seed tins the same way, so I didn't argue.
Demineralization cartridges
The PureGuardian demineralization cartridges in our data are numbered by size:
- Cartridge 1 (FLTDC): the listing says it lasts 1,000 hours
- Cartridge 2 (FLTDC20): the listing says 700 hours of run time
- Cartridge 3 (FLTDC30): the listing says 500 hours
The number has to match your humidifier, so check the manual. The EPA says to use demineralization cartridges only if the maker supplies or recommends them, and to watch for white dust as a sign minerals are getting through.
Germ Guardian vs Levoit
People compare these two brands often. They're both on Amazon US with air purifiers, filters and humidifiers. The comparison block on this page lays out how their listings differ in our data. In short, the two brands lead with different numbers. Germ Guardian listings tend to state CARB certification and a UV-C light; Levoit listings tend to state a CADR and a noise level. Neither set is the whole picture. The Levoit brand page lists that brand's models the same way this page lists Germ Guardian's.
Reading a Germ Guardian listing
A few habits from 34 years of reading data plates:
- Read the model number with its suffix. AC4825E and AC4825W are the same tower in two colors. Other suffixes can mean a bundle or a two-pack.
- Match the filter letter to the model, using the compatible-models line on the filter listing.
- Look for CARB on the listing, then confirm the model on CARB's list if it matters to you.
- Look up the CADR in the AHAM directory if the listing doesn't give one.
- Find the manual before the first filter change, not during it.
The front of the box sells the machine. The back of the box and the data label tell you what you're buying.
Air purifier and humidifier safety
Air purifiers and humidifiers both plug into the wall and run for long hours, so set them where the cord won't be tripped on and the airflow isn't blocked. The EPA's air cleaner guide says to keep a purifier clear of curtains and anything that blocks airflow. For humidifiers, follow the maker's cleaning schedule and water type, and keep warm-mist units away from children.
Check the plate, match the letter, write down the date.
