When it gets stuffy indoors, we typically leave our porch doors open or crack a window to let in “fresh” air. However, we often forget just how polluted outdoor air is. Other than letting in a refreshing breeze, you’re also allowing bacteria, pollutants, and allergens into your home – all of which can cause wreak serious havoc on your lungs over time.

Germ Guardian AC5900WCA 3-in-1 True HEPA Filter Air Purifier Review

The ideal way to clean the air inside of your home is not by nailing your windows and doors shut, but rather by investing in an air purifier. The Germ Guardian AC5900WCA 3-in-1 Air Purifier has an excellent reputation for being a high-quality air purifier for large-sized rooms. Plus, it has most of the convenience features you’d ever need to make owning and using an air purifier an enjoyable experience.



Activated Granular Carbon Filter

Air purifiers work by suctioning in air through its inlet and passing the air through a series of filters. The AC5900WCA uses a 3-stage filtration system where its first line of defense is an Activated Carbon Filter. This filter traps large airborne particles and neutralizes odors from pets, cooking, chemicals, and tobacco, giving your home a scent-free but refreshing smell.

Germ Guardian AC5900WCA 3-in-1 Air Purifier

True HEPA Filter

After the larger particles get stuck in the carbon filter, the air is then pushed through a super-fine True HEPA Filter – the only filter of its kind that can trap microscopic particles as small as 0.3 microns in width with 99.97% effectiveness. If you suffer from seasonal or pet allergies, or your home is infested with dust mites, then you’ll need the awesome straining abilities of HEPA filters.

UV-C Germicidal Beams

The third and final step in the purification process is an optional UV-C ionizing beam. Any microscopic organisms that wiggle their way through the HEPA filter will not make it far after being exposed to this germicidal light. UV-C lights deconstruct the DNA build of bacteria and viruses, eliminating them from existence. The AC5900WCA is CARB compliant, so the level of ozone production by the UV-C light is far from hazardous to humans.

Germ Guardian AC5900WCA 3-in-1

338-square-foot Maximum Capacity

Air purifiers come in many sizes and shapes. Before you pick one up from the store, make sure you know in which room you’ll place it in and how large the room is. The AC5900WCA is suitable for rooms as large as 338 square feet. The AC5900WCA is more than capable of purifying the air in kitchens, offices, hallways, garages, and bedrooms.

3 Different Fan Speeds

The AC5900WCA does not have any smart sensors to monitor the quality of a room’s air, so you’ll have to manually choose between three available fan speeds. On low speed, the air purifier is virtually noiseless, making this the optimal speed for undisturbed sleep. Medium speed generates a quiet buzz that customers describe as “gentle white noise” that actually helps them get to sleep. On high speed, you won’t hear thunderstorms over the AC5900WCA.

Germ Guardian AC5900WCA Air Purifier

Remarkable CADR Ratings

CADR ratings are used to determine the efficiency of an air purifier at removing three types of airborne pollutants – smoke, dust, and pollen. Like most ratings, the higher the figure, the better the air purifier. The AC5900WCA scores 218 for smoke, 220 for dust, and 215 for pollen. Any air purifier with CADR ratings above 200 is going to be unquestionably awesome.

Built-in Timer Function

Unfortunately, the Germ Guardian AC5900WCA does not come with a remote control, nor is it compatible with the Guardian TE smartphone app. However, with the built-in timer function, you still get ultra-convenience without the fancy add-ons. To set the timer up, all you need to do is press the timer button to choose one of the four preset times (1, 2, 4, and 8 hours). After setting it up, let the AC5900WCA do its thing until it automatically shuts down.

Germ Guardian AC5900WCA 3-in-1 True HEPA Filter Air Purifier

Germ Guardian AC5900WCA vs. AC5350B

After reading our review of the AC5900WCA, you should have a general idea of what it can and can’t do. Now, let’s see how the AC5900WCA fares against other air purifiers on the market. We’ll start first by comparing it to its cousin model, the Germ Guardian AC5350B.

Germ Guardian AC5900WCA vs. AC5350B

Despite the 7-inch height disparity between the two (the AC5900WCA stands at 21 inches tall), the taller AC5350B has a smaller purifying capacity. This air purifier is designed for rooms of up to 167 square feet, slightly less than half that of the AC5900WCA. Knowing this, you’ll get the best results when placing it in bedrooms, single-car garages, or office units.

Another difference is the number of fan speeds available in each of these air purifiers. The AC5350B has five different fan speed options that produce varying levels of noise. The increase in fan speed options gives users more flexibility and improved cleaning efficiency compared to the AC5900WCA.

In every other regard, these two Germ Guardian air purifiers are identical in every way. They both purify air using a 3-stage filtration process (Activated Charcoal, True HEPA Filter, and UV-C) to eradicate odors, allergens, mold spores, pet hair, and airborne germs. Furthermore, they have built-in timers that offer a maximum of 8 hours of continuous cleaning before automatically shutting down.

Germ Guardian. AC5350B

Despite having more in common than not, the AC5350B CADR ratings are far lower than the AC5900WCA’s. It scores only 108 for smoke, 114 for dust, and 127 for pollen. This air purifier is half as efficient as the AC5900WCA in similar situations.

Germ Guardian AC5900WCA vs. AC4825

Once again, we’re going to compare the AC5900WCA to another Germ Guardian air purifier – the AC4825. In terms of style, the AC4825 has more in common with the AC5350B than the AC5900WCA. And it’s not just looks that the AC4825 shares with the AC5350B. This model is suitable for use in rooms with a maximum area of 167 square feet.

Germ Guardian AC5900WCA vs. AC4825

With appearance and coverage capacity out of the way, the AC5900WCA and AC4825 are pretty much packing the same heat. They both use the same 3-in-1 filtration system that uses a carbon pre-filter, a True HEPA Filter, and an optional UV-C light.

These two air purifier models also feature the same timer function (1, 2, 4, and 8 hours), the same HEPA filter indicator, and the same choice of three fan speeds. These two models are packing the same equipment but in very different housings.

But there’s one thing that makes the AC5900WCA far better than the AC4825, and that is its CADR rating. The AC4825’s CADR ratings for smoke, dust, and pollen are 108, 118, and 125 respectively, which is almost half that of the AC5900WCA when placed in the same room. This doesn’t mean that the AC4825 isn’t worth getting. If you need an air purifier for your bedroom, this would be the better option to get without overkill.

In the end, the only consideration to make before choosing between these two Germ Guardian models is how large of a room are you going to purify. That being said, we can’t deny that the AC5900WCA’s greater coverage capacity makes it the far more versatile air purifier of the two.

Germ Guardian AC4825

Germ Guardian AC5900WCA vs. Winix 5500-2

Finally, we’re going to exit the realm of Germ Guardians and compare the AC5900WCA to another model from another brand – the Winix 5500-2. We’ve spoken about this air purifier many times, and we still gush at how great of an air purifier it is.

Germ Guardian AC5900WCA vs. Winix 5500-2

First of all, the Winix doesn’t just have astounding CADR scores (232 for smoke, 243 for dust, and 246 for pollen), but it has one of the best-looking cases of all time. We know, looks aren’t everything, but c’mon! This thing is an absolute beauty!

In every other area of comparison, the Winix comes out on top. Firstly is the area coverage capacity where the Winix can handle large 360-square-foot rooms while maintaining its amazing CADR scores. But if we’re honest, there probably isn’t a room where the Winix’s greater coverage would significantly outclass the Germ Guardian’s 312-square-foot range.

Even though the Germ Guardian offers convenience with its built-in timer function, the Winix’s smart sensors make it the much more convenient air purifier. Its sensors constantly monitor the quality of a room’s air and automatically choose one of the four fan available fan speeds based on its readings. When the air has been thoroughly cleaned, the Winix will shut off. You don’t have to worry about under- or over-purifying a room with an inflexible timer.

Winix 5500-2

There’s so much more we could talk about the Winix 5500-2, but you can find all of that on another page. Instead, the main thing to take away from this comparison is that the Winix outshines the Germ Guardian in every way imaginable. Do yourself a favor and choose the WInix.


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Alen Dyson Levoit AirTamer Coway
Classic HP02 LV-H132 A310 AP-1512HH
1100 SqFt 300 SqFt 130 SqFt - 360 SqFt
10 x 17.8 x 26.8 in 8.7 x 6 x 24.9 in 8.5 x 8.5 x 14.5 in 3.5 x 0.8 x 1.8 in 9.6 x 16.8 x 18.3 in
21 pounds 8.62 pounds 6.5 pounds 1.76 ounces 12.79 pounds