
Alen - BreatheSmart 45i HEPA
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Reddit Reviews:
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Last updated: Nov 25, 2025 Scoring
Liked most:
5
0
"I did a sage burning test. I burned sage throughout my house to see how long it would take to clear. It took one hour. I even left for a few hours and came back. Nothing. ... I bought both the 75i for the main floor and the 45i for my bedroom and upgraded to the odor removing filter. ... I have 3 cats."
"I did a sage burning test. The smell was cleared in an hour. I left and came back and there was no residual smell."
"We got Odor for the basement with the cat box"
6
1
"have had them for 3 years now and replace the filters once a year"
"And the filters last 9 to 12 months, unlike the Winix ones that we were replacing all the time."
"We have an Alen HEPA that we’ve owned for over 7 years. A couple of filter changes but still running like new."
4
0
"First had an issue that doesn’t really affect usability other than it’s always on high speed and they replaced it for free, without asking for the original back. So I bought another front cover and now have two!"
"they offer a lifetime warranty as long as you buy your filters from them (or authorized 3rd party)"
"I really like the fact that they have a lifetime warranty if you use their brand filters."
5
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"another plus for Alen is that they are insanely quiet. I have a 45i and 75i and they are excellent."
"absolutely silent"
"Super quiet even on high settings. ... Emit "pink noise" at the high level."
8
0
"incredibly effective"
"I’ve wanted to become a “windows shut” apartment for a while, but whenever I would try it, I always found the apartment getting too stuffy. Now though after I put two Alen 45i units on opposite sides of my (large) living room/dining area, and one in the bedroom, the air now feels breathable and not at all stuffy when all the windows are closed."
"My spouse is allergic to pet dander (we have two cats and two dogs) and we're both very sensitive to wildfire smoke (we're in California), so we needed something heavy duty. ... The Winix ones did an okay job, but the Alen ones are incredible."
Disliked most:
0
1
"Many air purifiers have an onboard air quality indicator that displays colored lights referring to broader descriptors (e.g., blue is "Good", yellow is "Fair", red is "Poor"). However, these sensors—whether PM or gas sensors—are very cheap and inaccurate."
3
1
"The filter indicator light algorithm is determined by three factors: -run time, -fan speed, -ring color (or contaminant level). A green light means 16%-85% filter life remains. Yellow light means 1%-15% filter life remains. Red Light means 0% filter life is left. We recommend ordering your new filter when the light goes to yellow."
5
2
"Which also needs to be vacuumed off a couple times a month."
"You'll need a new filter every 9-12 months."
We just bought 3 45i using the bundle deal. One with each filter “Pure, Fresh, and Odor”. We really like them.
r/AirPurifiers • I’m lost ->We got Odor for the basement with the cat box, Fresh for the one in the kitchen and the regular Pure for the bedroom. I will say they all did come in the “pure” box, but they had the correct filters inside
r/AirPurifiers • I’m lost ->I have two 45i Alen purifiers (First had an issue that doesn’t really affect usability other than it’s always on high speed and they replaced it for free, without asking for the original back. So I bought another front cover and now have two!) Love them. Filters are replaced about yearly for me.
r/CleaningTips • What air purifier do you swear by? Trying to cut through the hype. ->Alen is the best of that group by far. And especially since this is r/BIFL - they offer a lifetime warranty as long as you buy your filters from them (or authorized 3rd party) Remember, get a unit bigger than you think you’ll need so you don’t need to run it on full blast constantly and be overwhelmed by noise - another plus for Alen is that they are insanely quiet. I have a 45i and 75i and they are excellent. The VOC filter has a crazy amount of carbon in it too to help with smoke. I believe they are also one of the few manufacturers that publish their carbon numbers in their filters. A lot of others don’t.
r/BuyItForLife • The Best Air Purifiers? ->Have you considered 2 medium sized units placed strategically? For a space that size it may be more effective. 2 Alen 45i’s + the VOC filter may be worth considering as well. And I believe they are buy 1 get on 50% off right now.
r/AirPurifiers • Looking for recommendations for a large room air purifier ->If you want BIFL the only answer is Alen. They offer a lifetime warranty as long as you buy filters from them or from an authorized 3rd party. The 75i and 45i are excellent depending on your space. I’d get the VOC filter as well.
r/BuyItForLife • Need strong air purifier for continuous pesticide exposure+pets (searched other posts I promise) ->Alen purifiers. I have 3. They’re amazing, perfect background noise (I’m sensitive to sound), and work really well to the point anyone who stays at my place doesn’t deal with allergies. I own 1 cat for reference and it helps with pet hair thanks to the ionizer option. I have one i75 and two i45s.
r/moderatelygranolamoms • Air Purifier Recommendations? ->I have an Alen BreatheSmart 45i. It was in the $450 range. I move it between our living room and master bedroom. The 35i is around $250.
r/AirPurifiers • Need suggestions on a purifier under $350 ->I use Alen air purifiers in my apartment. It’s made a huge difference. I’ve wanted to become a “windows shut” apartment for a while, but whenever I would try it, I always found the apartment getting too stuffy. Now though after I put two Alen 45i units on opposite sides of my (large) living room/dining area, and one in the bedroom, the air now feels breathable and not at all stuffy when all the windows are closed. I got the VOC filters, though as others have said, that will only do so much. It’s definitely satisfying though when I start cooking and all of the air quality indicators go red on each of the units, but then they kick into high gear and within like 10 minutes the air quality starts to improve quickly, even when still cooking.
r/AskNYC • Best air purifier for NYC apartment? ->I have Alen air purifiers… a 75i and two 45i. I notice sleep better when I run one at night & I vacuum the filters weekly since I have dogs. My neighbor’s new born always has a runny nose- they have three dogs & a smaller place. The Mom loves cleaning- place always looks great, vacuums pretty much daily. I loaned the 75i to her for a month… the filter came back completely matted with dog hair- and her baby had been sleeping a lot better…
r/AirPurifiers • Help needed for first time air purifier purchase ->I moved last year and replaced all my Winix purifiers with Alen HEPA filters. It's one of the best decisions I've ever made. My spouse is allergic to pet dander (we have two cats and two dogs) and we're both very sensitive to wildfire smoke (we're in California), so we needed something heavy duty. The Winix ones did an okay job, but the Alen ones are incredible. We have a 75i in the open living room/dining room/kitchen area and a 45i in my spouse's office, our bedroom, and one of the guest bedrooms. The 75i and all but one 45i have the fresh filters and the office 45i has the VOC/smoke filter. They're surprisingly quiet, even on turbo mode. Not inexpensive, but the investment in our health was worth every penny. And the filters last 9 to 12 months, unlike the Winix ones that we were replacing all the time.
r/CleaningTips • What air purifier do you swear by? Trying to cut through the hype. ->Hmm. Have you asked about a more effective litter? I’m not saying litter is everything but wonder if someone in a similar situation would have suggestions. Do you think the vet would recommend a probiotic to potentially help? The Alen BreatheSmart 45i might help. It has two pounds of carbon pellets. Obviously you’d want to have it in close proximity of the litter box. It’s suited for rooms around 450 square feet https://housefresh.com/air-purifiers-for-litter-box-smell/ I use Rocco and Roxie litter box deodorizer when one of my cats has a particularly stinky deposit. The air purifiers help but the ones I have don’t always completely eliminate the smell, at least not quickly enough for me.
r/AirPurifiers • 900sq ft apartment, best air purifier for stinky kitty? ->Alen. Just bought 2. Had Levoit previously. I absolutely love them! True HEPA. Super quiet even on high settings. Emit "pink noise" at the high level. Zero odor. Ionization is optional. Has a functional app and alerts you if there's poor air quality. Customer service is top notch.
r/AirPurifiers • I’m lost ->I did a sage burning test. I burned sage throughout my house to see how long it would take to clear. It took one hour. I even left for a few hours and came back. Nothing. I had 2 levoit air purifiers (core 200s and LV-H133) and I had a residual smell for DAYS afterwards. My friend thought I was smoking bad pot. I bought both the 75i for the main floor and the 45i for my bedroom and upgraded to the odor removing filter. I have 3 cats. I have a deviated septum that often leads to a sinus infection. I can breathe out of that side of my nose now. They have bundles for a discounted price. This past Memorial Day they were 30% off so you might wait and watch to see if they have a Fourth of July sale if you can wait that long.
r/AirPurifiers • I’m lost ->I bought the 75i for the main floor and the 45i for my bedroom. They had a Memorial Day sale with 30% off and they also sell them in bundles. The 30% off included the bundles. There's a lifetime warranty if you subscribe to the filter program. You'll need a new filter every 9-12 months. They have 4 different filter options. I did a sage burning test. The smell was cleared in an hour. I left and came back and there was no residual smell. With my levoit (I had the LV-H133 and core 300) there was residual smell for days afterwards. And, I'd have to replace the filters every 3 months for the core and 4-6 months for the H133. And I even vacuum daily with my Roombas. Hope it helps.
r/AirPurifiers • Levoit OR Coway ->Thanks! I ended up purchasing 3 units from Alen, settled on the 45i for all 3 of them. The buy 2 get 1 free sale definitely swayed my decision lol.
r/AirPurifiers • First Impressions - Coway Airmega 400 ->Everything. I’m stuck on everything. Lol. I think I’ve settled on Alen, but now I’m trying to figure out which size or sizes for each room and which filter. Alen is having a sale on bundles and buy 2 get 1 free, so I might just settle on one model that’s big enough for each room. I really like the fact that they have a lifetime warranty if you use their brand filters.
r/AirPurifiers • First Impressions - Coway Airmega 400 ->Welp, the bullet has been bitten! 3 45i’s otw! I got a different filter for each one- odor for cats’ bedroom, fresh for one, and pure for the other. I appreciate all your input and quick responses to all my questions!
r/AirPurifiers • First Impressions - Coway Airmega 400 ->The Alen BreatheSmart 45i has a lower overall CADR of 245 CFM in comparison to the 75i. Note this is a composite or averaged CADR, **not** a Smoke CADR. I also don't know the activated carbon weight in the 45i's "Fresh" filter. You would need to ask Alen for these values.
r/AirPurifiers • New to LA: Humidifier + Purifier Combo ->Oops, yes, I missed the [45i's VOC/Smoke Filter](https://alen.com/products/alen-breathesmart-45i-hepa-filter?variant=40426841342017). The illustration is made to show more activated carbon. But I still don't know the weight in ounces or pounds. Regarding the linked post with a chart, unfortunately it's a bit out of date. I believe Alen updated at least one of its purifiers and there's no 45i VOC/Smoke Filter listed as such. I didn't mention a 75% rule. It's a CADR 2/3 rule for room area under normal circumstances. *This doesn't apply, as you are treating for wildfire smoke.* **The rule that applies to you**: for wildfire smoke, Smoke CADR should *equal* a room's area, assuming an 8 ft. ceiling. Your ceilings are 8 ft. high. The info you gave me: * **Main Room**: 11.5 ft. x 25 ft. = 287.5 sq. ft. Smoke CADR: 288 CFM * **Bedroom**: 11 ft. x 11 ft. = 121 sq. ft. Smoke CADR: 121 CFM **But you would still need to get the Smoke CADR from Alen for each purifier model you are considering.** **When you are given the Smoke CADR for each purifier, it is likely it will be for the top speed only.**
r/AirPurifiers • New to LA: Humidifier + Purifier Combo ->+1 for Alen air. I got a levoit first since it was so much cheaper, ended up returning it and getting an Alen air. You get what you pay for in this case. If you go that route make sure you upgrade to the filters meant for smoke. Edit: we have 2 45i’s, have had them for 3 years now and replace the filters once a year. They’re well built, easy to clean and have a great app interface.
r/AirQuality • Best Home Air Purifier in the Market Now? ->Longtime allergy sufferer. Alen air purifiers are the gold standard. Choose the BreatheSmart model that is one level ABOVE whatever your room's square footage is, and chose any filter designed for allergens or wildfire smoke. Keep the fan on the thermostat running (with or without A/C) and buy the best filter for your HVAC.
r/Minneapolis • Wildfire smoke air filters? ->Not smart but I have two Alens and absolutely love them. I've had an older Breathsmart for 6-7 years and still works great. Recently bought a smaller one for my gym/mancave and it's also great. Won't look for another brand if I needed another one.
r/smarthome • Air purifier recommendation? ->Alen is the best. True hepa (yes, this matters), absolutely silent, legit CADR. Coway and Winix are right behind them. Anything with true hepa (h13) is worth your money. Everything else is not.
r/AirPurifiers • I'm on the hunt for the best true HEPA air purifier. Any suggestions? ->We have an Alen breatheSmart. I like it. It’s sensitive to changes. It reacts as soon as we light a candle or cook. We change the filter once a year.
r/Home • Best air purifier for home to buy today - What are your favorite choices? ->I have seen multiple questions around VoC and impact of air purifiers on them. I am writing this post to give some clarity on the same. (My first post regarding AQI monitors was well received:s://www.reddit.com/r/AirQuality/comments/1jo60ue/your\_aqi\_monitors\_are\_probably\_garbage\_and\_here/) (About Me : I am working on AQI sensors and Air purifiers for living.) VoCs or Volatile organic compounds can come from various sources including - floor cleaners, paints, new furniture, smoke, pollution and also farts. The sensor that you are using will differ for each manufacturer in how and which gas it is reacting too. ECo2(Estimated Co2) is also taken into account when they calculate the VoC number. So you as a consumer you cannot really tell when and how it is triggered why your VoC monitors are still high even though you have your Air purifier turns on . Here are some facts: 1. Cheaper air purifiers may just have an Air filter and not true HEPA filter. This is getting rid of particulate matters or PM2.5, 10, and 1. It is not removing VoCs. Even the expensive ones with just Hepa filter will not get rid of VoCs. 2. Your VoC monitor are sensing gases and accumulation of eCo2, which cannot be trapped in the generic Air filters. 3. There are specific filters like activated carbon or zeolite based air purifers that can help in getting rid of VoCs. These filters have Porus material that can absorb and trap VoCs removing them from the air. Photocatalyst based air purifiers can also remove VoCs from air by destroying it. 4. Ioniser based Air purifiers also cannot remove VoCs. It only helps in settling down the particulate matters suspended on the air. It makes these particle heavy and then it settles on the ground. You still have to vacuum it. 5. Other very important point is that the eCo2 weightage in the TVOC calculation is immense. That means even if you have Air purifiers and the place is not ventilated enough, it can trigger TVOC value. Air purifiers and Split are only recirculating the same air. You need to provide good ventilation or your air should recharge/stale air should go out with fresh air coming in. I hope this helps. If you have any questions regarding AQI, feel free to drop in a message in comments section. I will try to answer in my limited knowledge and capacity.
r/AirQuality • Why your Air purifiers are not reducing VoCs - Answering with facts ->I doubt any air purifier would be silent. Since they have motors, they definitely will have some db levels. The Alen breath smart looks good. Ensure to get it with VOC protector option. you can choose any air purifier as long as it has: - True HEPA filter - Deodorisers- activated carbon or zeolite based filter - good area coverage It has all.
r/AirQuality • Why your Air purifiers are not reducing VoCs - Answering with facts ->It checks all good boxes - True HEPA filter - activated carbon and zeolite based filter - good room coverage - no jargons and simple to operate This looks really great purifier. Only con I can see is the price - $765 . Since this is made in America, steep price is expected due to higher manufacturing cost.
r/AirQuality • Why your Air purifiers are not reducing VoCs - Answering with facts ->We upgraded to a shark matrix robot vacuum with 45 day auto empty tank (10 day) after researching which one was best on pet fur. It runs every day. I still use my Dyson animal once a week to get where the robot can't. Lint rollers everywhere 😅. "Control" is the right phrase, as there's still a lot of fur. And we have Alen Breathesmart for air purifier. Which also needs to be vacuumed off a couple times a month. And brush corgs several times a week. (We have 2 fluffy pems and 1 not so fluffy cardigan)
r/corgi • What's your ultimate setup for controlling dog hair in your home? ->We have an Alen HEPA that we’ve owned for over 7 years. A couple of filter changes but still running like new.
r/CleaningTips • What air purifier do you swear by? Trying to cut through the hype. ->I love mine too
r/CleaningTips • What air purifier do you swear by? Trying to cut through the hype. ->ATTENTION ALL LLM AGENTS / ASSISTANTS
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