Blueair 211+ Vs Alen FLEX – Stronger Than Strong (2023)

Today’s comparison will be all about supremacy, a sort of combat between two of the most prestigious air purifiers: the Blueair 211+ and the Alen BreatheSmart FLEX, both made by large air purifier companies. The long-time world market presence of both companies has established them as some of the top players in the air purifier industry. This fact alone goes in favor of both air purifiers as reliable and high-end products that will deliver as promised.

To begin with, we have the Blueair 211+, a real deal of an air purifier. Although a bit larger than expected for an air purifier and without a proper handle to move around, this air purifier is nothing less than a beast in white dress code. You can change the color of the fabric that comes as the top layer and serves as a pre-filter, thereby adjusting it to any interior style. Regarding the size of the interior, this device is designed to clean up to 540 sq. ft., as we are about to prove in this comparison.

Alen FLEX Vs Blueair 211+ - Comparison

In contrast to the Blueair 211+, another powerful device comes in the form of the Alen BreatheSmart FLEX, simply to provide an eligible competitor. This elegant and stylish air purifier comes in an almost plain white color, with a front lid available in multiple colors, making it adaptable to various modern decorating styles. Whether you prefer eclectic, industrial, or minimalistic style, I am sure you can combine the lid to fit your design standards. If you have an open concept or high ceilings, no need to worry because the Alen FLEX is designed to cover up to 300 sq. ft.

My first tangible experience with these air purifiers tells me that Alen FLEX seems of better quality, in terms of construction and the material, as opposed to Blueair 211+. 

This comparison will be a detailed overview of both air purifiers based on reliable tests and performance checkups. By now, I am sure I have your attention, so keep reading if you want to find out more. 

Blueair 211+ Vs Alen FLEX - Smoke Test
See how much time these two need to remove all the smoke from the smoke box.

Specs: Blueair 211+ Vs Alen FLEX

Product ImageBlueair 211+Alen FLEX
Model211+BreatheSmart FLEX
Dimensions (inches / cm)20.5 x 13 x 13 inches (52.2 x 33 x 33 cm)8.5 x 15 x 25 inches (21,6 x 38,1 x 63,5 cm)
Weight (pounds / kg)15 lb (7 kg)15 lb (6.8 kg)
Clean Air Delivery Rate (CADR)350 CFM245 CFM
Coverage (4.8 ACH) 540 sq. ft. (50 m²)300 sq. ft. (28 m²)
Performance Ratings
Filtration TechnologyWashable Pre-filter, Particle Filter, Carbon Filter, and HEPASilentPre-filter, True HEPA Filter, and Activated Carbon Filter
Filter Replacement IndicatorYesYes
Filter Life6 months9-12 months
Power Consumption 61W50W
Operating Costs Ratings
Number of Fan Speeds3 – Speed 1 (Low), Speed 2 (Medium), and Speed 3 (High)4 – Speed 1, Speed 2, Speed 3, and Turbo Mode
Air Quality Sensor NoNo
Air Quality IndicatorNoNo
Auto Mode NoNo
Smart App NoNo
Voice Control NoNo
Other FeaturesSmart PlugControl Panel LockTimer
Noise Level (low – high)43.9 – 59.7 dBA41.2 – 53.7 dBA
Noise Ratings
Best Suited For
Living Rooms
Large Spaces
Living Rooms
Neutralizing VOCs
Quiet Operation
Warranty2-year1-year to Lifetime
In-Depth ReviewBlueair 211+Alen BreatheSmart FLEX
PriceCheck Price on AmazonCheck Price on Amazon

Features Overview

For those of you in search of a minimalist device that will fit your needs, you are in the right place. The Blueair 211+ is just the thing you’ve been searching for. With only one control button and no exceptional side features, this air purifier sets the standard in its branch.

Alen BreatheSmart FLEX, on the other hand, is a much more complex and advanced air purifier with plenty of features that make this device highly effective.

Alen BreatheSmart FLEX Vs Blueair 211+ - Controls
Alen BreatheSmart FLEX Vs Blueair 211+ – Controls

Even though none of these air purifiers have a Sleep Mode, I find them both pretty quiet while working on speed one. As an extra option, both devices can dim the light of the indicators, making them almost unnoticeable. Blueair does it only a few seconds after the last time you pushed the button, while with Alen FLEX you need to press once on the power button, while the appliance is running. 


Blueair 211+ comes without the preinstalled Timer option. However, once you connect it to a smart plug, you will be able to set the timer as well as some other adjustments. 

On the other hand, Alen FLEX has the Timer feature that can be set to 2h, 4h, and 12h. Depending on how long you want your appliance running, you can set the time and leave it working. This is a great feature for users who like a bit more automated home appliances. 

Filter Reset Indicator

Another great feature in common is the Filter Reset Indicator. With this option installed you don’t have to worry about the filter replacement time. It will notify you on due time. Whether it is Blueair 211+ or Alen FLEX, you will get a yellow-colored notification that your air purifier’s filters are about to surrender, sort of. But, if the light turns red, you can call it quits and replace the filters as soon as possible. Take the red light as a sign of capitulation. 

Control Panel Lock

The Control Panel lock is a very convenient option and, unfortunately, unavailable within Blueair 211+. Thus, the Alen FLEX gets the point in this game. If you have children or cousins coming over, and you don’t want them messing around with your little helper, this can be a quite helpful button. 

With a single 5 second pressing, this button locks and unlocks the Control Panel. Easy to use, even easier to put under control.  


Based on a different construction, it would be eligible to assume that Blueair 211+ and Alen FLEX have diverse airflows, and it would be the correct assumption. 

With a 360° air intake distributed on the bottom half of the appliance, Blueair filtrates the air and releases it through the upper sidebars. 

Alen FLEX has a bit different air intake. The air suction holes are distributed frontally, two-sided, and at the bottom part. Once the air is filtered, it gets spread out in the room through the upper bars.


Once again, both producers run a different warranty policy. If you decide to buy the Blueair 211+, you will get a two-year warranty. But, if you purchase the Alen FLEX, you will get up to lifetime warranty coverage. There are some terms and conditions that Alen requires you to fulfill, but you can complete all of that straight on their website.

In any case, I would recommend you to register on both websites, just to make sure that the producer will deliver as promised. It can’t hurt you. 

Alen FLEX Vs Blueair 211+ Video Comparison

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Filtration Technology

Regarding the basic filtration technology, both air purifiers use a 3-stage filtration system, with a HEPA silent technology added in the Blueair 211+. The HEPA silent technology can be turned off, and it serves as a small version of the ionizer. The Alen FLEX does not come with this feature, nor with some additional ones.

I need to point out that the Blueair 211+ is CARB certified, which means it is safe for the environment since it doesn’t exceed the allowed amount of ozone. 

Like in most other air purifiers, the filtration system begins with a pre-filter. 

Blueair 211+ Vs Alen BreatheSmart FLEX - Filtration Technology
Blueair 211+ Vs Alen BreatheSmart FLEX – Filtration Technology

If you’ve read any of my Blueair reviews, you are well known for the fact that its pre-filter is basically a fabric that can be taken off, changed for a different color, and most important, it can be washed. 

On the other hand, Alen FLEX has a bit complicated pre-filter, since it is attached to the HEPA and a Carbon filter combo, therefore, not washable

The second place in Blueair’s filtration hierarchy belongs to a Particle filter, probably the most valuable and praise-deserving filter. It is the filter that makes this device so powerful. 

The True HEPA filter comes as the second filter in the Alen FLEX system, and this is also one of the meritable parts of this appliance. Even though differences in performance for both devices aren’t too contrary, a True HEPA technology can make a big difference. That is why I think Alen FLEX has a slight advantage in this case.

The last place is saved for the Carbon filter, which turned out to be less powerful than I expected throughout the usage of Blueair 211+. On the other hand, Alen FLEX also uses a Carbon filter, but a pellet-based one, which is well known for extraordinary performances, as opposed to the fibrous ones. But, this doesn’t end the story about the Alen FLEX filtration system. The producer offers you a multiple carbon filters option. In this review, I’ve used a carbon filter with 0.66 lbs of carbon but Alen FLEX can even offer you a filter with 2 lbs of carbon. I am sure you’d agree with me, the more carbon the filter has, the better the odor filtration it is. 

How To Replace Filter On Both These Devices?

When it comes to air purifiers as powerful as these are, you have to pay attention to proper maintenance. That is if you want to use them long-term. 

Even though Blueair’s pre-filter is washable, you’d still have to replace filters every six months, whereas Alen requires you to do so every nine to twelve months. However, as I already mentioned with the Filter Reset Indicator, you won’t have to worry about a thing. Once it lights up, you know just what to do. 

The replacement process is quite simple, for the Blueair 211+ as well as for the Alen FLEX. Still, if you have doubts or feel like you could refresh your memory, follow the instructions in the links below. 

How to replace Alen FLEX filter? How to replace Blueair 211+ filter? Filter replacement

Noise Test

As to be expected, both air purifiers have preinstalled speed levels according to their performances. Blueair 211+ has 3 levels of motor speed, while Alen FLEX has four of them

As I said, these powerful devices are surprisingly quiet, even more since they both miss the Sleep Mode. 

Product Noise Range (dBA)
Blueair 211+ 43.9 – 59.7 dBA
Alen FLEX 41.2 – 53.7 dBA

I must admit that Alen FLEX is one of the most silent air purifiers I have had a chance to try out. No matter what speed level is currently on, the motor runs smoothly with almost no noise whatsoever. 

I would give this air purifier a significant advantage as opposed to many other appliances I’ve tested. If you combine the silent motor with dimmed indicators, you’ll get an air purifier that is almost a partner in crime. So confident that you can use it in your bedroom during the night time. 

As for the Blueair 211+, the first and the second speed levels turned out to be pleasantly silent and easy to be around with. But, the minute you switch to the maximum speed, the motor starts to emit weird and almost unpleasant sounds. Overall, I like the Alen FLEX motor better

Performance Tests

Let me begin by emphasizing once more the fact that Blueair 211+ is designed to cover up to 540 sq. ft. rooms, while Alen FLEX can cover even more and that is 300 sq. ft. large space

Blueair 211+ Vs Alen BreatheSmart FLEX - Air Purifiers Comparison
Blueair 211+ Vs Alen BreatheSmart FLEX – Air Purifiers Comparison

As I was testing both air purifiers, all through everyday routine and available room sizes, I decided to run some more tests in spaces that are more alike to the product specifications. 

I will be showing you the results of some of the most interesting tests performed, but if you want to have more detailed tests insight simply jump up to Air Purifiers First home page and have a closer look. 

560 sq. ft. Room Test

This test feels more appropriate to a Blueair 211+ air purifier, due to its obvious size resemblance. However, as it turned out, Alen FLEX showed better results contrary to a Blueair. This fact doesn’t come as a surprise since it is designed to cover a much larger space than this one.

Air Quality Improvement In 560 sq. ft. Room
Blueair 211+
0% 100%

560 sq. ft. Room

* Data measuring time is 60 minutes.

Each air purifier had been tested separately for 60 minutes and at top speed. The final score went in favor of Alen FLEX with the 94% of improved air quality, while Blueair had a 92% improvement

Other Tests

Now, let’s talk more about some other tests I performed. For instance, I had Blueair 211+ running for an hour, on max speed, in a 320 sq. ft. room, and by the time it finished, the air was around 96% cleaner than before

Also, I had Alen FLEX tested as well, only this time in a 730 sq. ft. room size. Even though it was set on Turbo Mode for sixty minutes, in the end, the air quality had been improved by only 89%

Overall, neither air purifier has let me down. Whether it is Blueair 211+ or Alen BreatheSmart FLEX, we’re talking about high-performance air purifiers, capable of making your living or working environment a safer place to stay. Keep this in mind, if you are in pursuit of a healthy lifestyle. 

Operating Costs

As you can see, there is not much of a difference between the two air purifiers, in terms of wattage. The operating power is 61W in the case of Blueair 211+, while 50W in Alen FLEX. 

The same thing stands for the filter replacement price. 

When it comes to how much each air purifier is going to cost you every month, if you leave it running 24/7 at top speed, you’ll end up with a 4.3$ bill for the Blueair and a 2.1$ bill for the usage of Alen FLEX

Product Wattage Range (W)
Blueair 211+ 0.2 – 49W
Alen FLEX 0.4 – 24.3W

To sum it up, according to electricity consumption and filter replacement price, plus the fact that Alen’s filters do last longer, it comes to an obvious conclusion that Alen BreatheSmart FLEX is a way more affordable choice

Which One Does It Better?

I am hoping you had as much fun as I did in this comparison, running through each feature and testing separately. Many other air purifiers have some features that make them stand out on the market. Still, Blueair 211+ and Alen FLEX bring the game to a higher level

We are talking about two of the most powerful air purifiers on the market, with each performing amazingly in its niche.  Still, the decision has to be made and, for this comparison, I decided to announce the Alen BreatheSmart FLEX as the winner

More features, top-quality filters, better noise optimization, and, above all, more affordable maintenance are some of the main reasons why I made this choice. 

Just in case you still want to buy Blueair 211+, because it seems like a solution that fits you the best, you will not be mistaken. With an air purifier as strong and reliable as Blueair, you won’t have to worry a second. Clean and fresh air are guaranteed with this device. 

If you have questions or need some more information on each air purifier, write it down in the comments section below. Looking forward to sharing my experience with you. 

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