Cloud 9 Sterile-Aire 300 HEPA Air Purifier

The Cloud 9 is no longer available, but Sterile-Aire still sells the SZ-101 Steril-Zone Room Air Purifier.

I’ve had allergies for so long that I can’t remember what it’s like not to be stuffed up. My dogs also seem to suffer from many of the same pollen, dust mite and mold allergies as I do, only their response is itching. Between us, we can usually tell when the pollen count or mold count is high. After years of tolerating my allergies, it came as a surprise to me the first night I plugged in the Cloud 9® Sterile-Aire® 300 air purifier.

The fan noise kept me awake for a few minutes that first night, but I soon conked out. But my sleep was interrupted four or five times, as I woke up, took a deep breath, muttered to myself “I can breathe!” and promptly fell back asleep.

While my sleep patterns have evened out to the point where I sleep the whole night through, my amazement over the Cloud 9 continues. I can breathe! I’ve now had my first good night’s sleep in twenty or thirty years – where my breathing is easy. Even the two dogs and a cat who sleep on the bed with me aren’t enough to clog my nose, unless they’re snuggled up too close to my face. And my girlfriend is thrilled – I don’t snore anymore!

The Cloud 9 is a substantial unit: 20-3/4” high, 25-5/8” across, and 12” thick. Actually, that translates to about the size of a 27” television set. In fact, for ease in moving the unit from one room to another, I put it on an old, wheeled TV cart. While that’s not specifically the way the manufacturer recommends mounting the unit (more on that later), it served my purpose of making the unit mobile.

The Cloud 9 Model 300 is designed to handle air in a room with up to 300 square feet of floor area. According to the manufacturer, the unit will filter out 99.99% of airborne bacteria and viruses, and 100% of ragweed, pollen spores, mold, fungi, dander, dust, lint and all other typical allergenic air contaminants. It will also take out 100% of tobacco smoke particulates one micron and larger. The company says the unit will operate at this efficiency level for 3 to 7 years, which is the typical useful life of the unit’s Super-Lung® HEPA filter. (HEPA stands for High Efficiency Particulate Air Filtration, and a true HEPA filter like this one is the most efficient type of filtration system on the market.) The HEPA filter can be replaced at that time, with a minimum of effort. The useful life varies depending upon how many people use the room, how much outside contaminated air is allowed into the room, and how often the first filter (prefilter) is changed.

The Cloud 9 first filter looks like a miniature version of a fiberglass furnace filter. It’s got the cardboard edges, and the metal honeycomb, too. It’s actually a specially-designed, highly efficient fiberglass filter, coated with a viscous substance to make it more attractive to particles. Its purpose is to collect dust, lint and large and heavy particles before they hit the charcoal filter, the squirrel-cage blower motor, and HEPA filter. By filtering out a large portion of the big stuff right off the bat, the life of the HEPA filter is dramatically extended.

The 16” x 7-1/2” first filter is amazingly efficient. In our test house, we have an electrostatic furnace filter (which gets washed monthly) and an air conditioning system which runs much of the time. We vacuum up tons of stuff at least once or twice a week with a high-efficiency vacuum cleaner. Still, with four people, three cats and two dogs running through the house, plus suburban air filled with year-round pollen problems, the first filter fills up quickly with pet hair and what’s known as “Texas white dust.” The manufacturer recommends replacement every thirty days; in our situation, two weeks seems more appropriate. (We were able to extend the life of the first filter a few more weeks by carefully vacuuming the filter when vacuuming the house.) If you have a bad allergy problem, and you want to continue living with your pets, replacing the first filter frequently is a good investment, running $3 to $6 each (plus shipping), depending on quantity.

The filter is very easy to replace. A plastic grid on the right side of the unit slides up and pulls out, revealing the prefilter. Slide that up and out to replace, then put back the decorative grid.

The next filter in line behind the prefilter is a charcoal odor filter. This activated charcoal filter adsorbs over 500 types of odors. With continuous use, it will become saturated with odor, and need to be replaced. If it’s not replaced, the charcoal will begin to release the collected odors back into the room. That happens at around 6 months with heavy use, and 1 year with light use. The filter is a Carbonweb®, which has the activated carbon on a pad, contained within a nylon mesh “bag.” The flexibility of the pad makes it a little difficult to keep vertical in its space without sagging, but it fills most of the space allocated to it. A cardboard rim, as found on the prefilter, would help make the carbon filter work more efficiently. The pad is about 3/4” thick, which is far thicker than the carbon filters in other units we’ve seen. Replacement cost is $34.50.

One problem we noted was that the dust collects in a few places where it’s not supposed to be. First, during our test period we regularly found some dust on the decorative intake grill. That was easily cleaned during our regular vacuuming. Next, more dust collected on the cardboard edges of the prefilter, and some made it past the prefilter to the charcoal filter. Some dust even made it to the next stage, collecting on top of the blower. This indicates to us that not all of the air is going straight through the prefilters. We’d prefer to see things a little bit tighter, so that more air flows through the filters before heading to the HEPA. (The manufacturer tells us that it’s not a problem as it stands, as the HEPA will catch anything that slips by. Still, the more you catch in the prefiltration stage, the longer your HEPA filter will last.)

The Cloud 9 is unusual in that air is pushed through the HEPA filter, not pulled through. This has the advantage of forcing more air through the filter, resulting in more air getting fully cleaned. It’s the “ram air” concept of ramming air through the system, and it eliminates a problem common to other air purifiers: air being pulled around – not through – the filter. With the Cloud 9, more air is cleaned, so the efficiency of the unit is much higher than other brands. And more clean air is what all of us with allergies are really after.

And this unit does work well. In one test we conducted, we allowed three cats to sleep overnight in a 10’ x 18’ office area.

The next morning, our two cat-allergic staffers reported extreme congestion, with one person doing some heavy sneezing. The Cloud 9 purifier was wheeled in, and allowed to run on full blast, with the office doors closed. Within an hour, both people reported that they were able to breathe easily, and the sneezing stopped. We went from bad allergies to no allergies at all in one hour with the Cloud 9 300!

The Cloud 9 has a three speed blower for maximum, normal and low/night settings. On max, the Cloud 9 purifies the air in a typical bedroom or office every four minutes. Set to normal, it will purify the air every six minutes. And on low, it completely cleans the air every eight minutes. The low setting works fine when there is minimal activity in the room, but will handle the dirty air from three cigarettes an hour. This is also the recommended setting for sleeping people, as the fan is at its quietest. Normal will handle the clean air needs of up to eight people. Max is recommended when you first move the purifier to a new room, if you have a lot of people in the room, or if you’re doing air polluting housekeeping chores such as bedmaking, dusting, vacuuming, or sweeping. The manufacturer suggests leaving the unit on high for at least half an hour after completion of those activities.

The Cloud 9 has one of the quieter fans in the business. Still, my girlfriend found the noise loud and distracting, even when set on low. After a day or two, though, she began to appreciate the white noise, which blocks out early morning traffic sounds and neighborhood dog barking. Now she doesn’t like sleeping without the Cloud 9 running, and she doesn’t have allergies! (Of course, Ms. Sensitive Ears won’t allow the machine to be turned on until after she finishes her nightly book reading. We must remain focused on those page-turners!)

The Cloud 9 also has a “pilot light” – an orange light that remains on while the unit is running. While we like the idea of having a night light shining in the room (it keeps me from bumping into the unit on those late-night bathroom runs), some might prefer total darkness. A piece of black electrical tape can solve that.

The Cloud 9 300 also has a built-in room freshener feature. A little plastic jar comes with the unit containing Lemon Fresh Formula 9D Cancelyzer®. I’m really not sure how well this feature works, as I’ve never used the feature in the almost 8 months of testing. The reason? When I had the little jar of Lemon Fresh sitting on my desk, the lemon-scent wafting out of the tightly-closed jar caused me to sneeze.

In the interest of doing a fair test, I decided to give it a try. Carrying the jar to the room where the air purifier is installed, I sneezed only three times. Installation took less than a minute, and turning on the Cancelyzer for two or three minutes resulted in a  heavy dose of lemon air. Unless you have some pretty heavy doggy odors, you don’t need to set the timer for long.

Our test continued by introducing our heavily allergic test subject, and the sensitive-nosed girlfriend, to the room. The sensitive-nosed one immediately went YUCK! and ran from the room. The allergic one didn’t sneeze from it, but said she wouldn’t want the scent in her house. The smell is too intense, too industrial smelling, like a bus station bathroom, she said.

I removed the jar, screwed the lid back on tightly, and relegated it to the back of the laundry room cupboard, with the other foul-smelling potions. What to do about the evil lemon smell in the test room? I turned the unit on high, and in five minutes there was no more lemon smell detectable. What a marvelous machine!

The manufacturer recommends that, for maximum performance, the air purifier be mounted high up on the wall, flush to the ceiling. They suggest putting it on the longest wall of the room, close to the left adjacent wall as you face the unit. In other words, it goes in a corner at the ceiling, so it pulls air down in from the longest wall and shoots it out along one of the short walls. This creates a vortex effect, circulating the air in a circle. The height of the unit gives it more opportunity to pull in the dirty air, as air tends to rise in the room.

Our experience has been that height of the unit isn’t critical (at least in our test rooms), as we had the unit placed above the height of most furniture, with an unimpeded air flow. While the unit has a long cord to reach an outlet near the floor, the idea of the big box hanging on the wall overhead, plus the cord dangling, didn’t get our decorator sense going in a positive direction. While the unit comes with a hanger bracket and three major wall anchors, we still don’t trust the quality of our wall construction. We’ll keep ours on the TV cart, thank you very much. We can move it to different locations depending on our need, and changing filters is much easier without having to use a ladder. If you have an industrial use for the air purifier, or place it in a hospital lounge or restaurant (as many customers do), the permanent bracket makes more sense. If you need more brackets to allow you to mount the same unit in another location, the company can supply them.

The Cloud 9 requires no more maintenance than a change of the pre-filter every month or so, and the charcoal filter every six to 12 months. A new HEPA filter for the 300, which is replaced after 7 years, is $105.50. (Other companies charge $70 for their HEPA filters, which need replacing every year.)
Every six months, the motor bearings need oiling. A small bottle (lifetime supply!) of special oil is provided inside the unit, in back of the charcoal filter. Three drops of oil are placed in each of two holes. If you live in a dusty part of the world, like here in Texas, we suggest that you vacuum the grill, the charcoal filter, and the fan when you change the pre-filter.

Overall, after nearly 8 months of daily use, we found the Cloud 9 to be a lifesaver. On bad allergy days, it comes to the office and keeps us all breathing easily. At night, it gives me incredibly pure air, which lets me sleep better than a baby. The sound level is tolerable, the efficiency is high, and my immune system sure appreciates the rest of a good night’s sleep. If I could afford them, I would have these units installed everywhere I go – work, office, you name it. The unit is far superior to the cheaper units we’ve tried, which haven’t produced the same degree of allergy-relief in our cat-and-dog allergen-filled test rooms. Even the dogs were breathing easier, with less itching during last fall’s allergy season.

We highly recommend the Cloud 9 Model 300, which allergists sell for $525. The company also makes the portable Model 150, good for a room up to 150 square feet  (such as an office). Allergists sell it for $325. There’s also a Model 800 for up to 800 square feet. The 800 has a built-in monitor that lets you know when the HEPA filter needs changing.

For quality and effectiveness, the Cloud 9 Model 300 air purifier is among the very best we’ve seen.

-Ross Becker

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Cloud 9 Sterile-Aire 300 HEPA Air Purifier
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