The very, very fine print pro and con hustle from Aerus Air Scrubber website:

* Published scientific studies conducted at Kansas State University demonstrated that ActivePure® Technology substantially reduces microbial populations on surfaces. The study's results are being provided solely for informational purposes. The study's results have not been reviewed by the FDA, EPA or any other governmental agency. Our products are not medical devices and are not intended to diagnose, treat, or cure any disease. We make no claims and no claims should be inferred as to the efficacy of our products to sanitize, disinfect or kill germs or other antimicrobials.

I would say most of the time these issues are directly related to high humidity levels in the home, poor or improper filtration. Probably more along the lines of bacteria production than mold.

Every house is different and so this subject is highly objectionable.

My opinion is that the gadget market is known for producing stuff that does little if anything to solve bigger more complex problems in the HVAC world.

Different types of fungus or bacteria require different amounts of water (in vapor form) to reproduce and grow. The majority require relative humidity (RH) of 60 percent or more, though some can survive and multiply in >20 percent RH. So the humidity levels of the home may OR may not be the issue, to illustrate the complexity of these kinds of problems.

I service the Katy, Texas area.

Thank you! We definitely knew this air scrubber was more of a “nice to have” and wasn’t going to solve any major issues. We felt like it went above and beyond, which we wanted to keep our air clean for our kids.

What’s blowing my mind is, did this proactive thing we did actually create a new issue??

I called the manufacturer today. They said it’s “almost impossible for mold to grow” inside the unit itself. Keyword “almost”. They haven’t heard of this happening to anyone else, or so they say. Seemed genuine, but who knows.

We have a 5 year warranty, so we may replace it like for like since there is now a hole in the ductwork which would need repaired if we simply removed it.

Also getting the ducts cleaned, again.

I hate not having a definite answer, but if we replace the scrubber with another scrubber (same brand and model) and it happens again I guess we have the answer.

The Aerus Air Scrubber is a device which generates hydroxyl radicals which, in turn, oxidize indoor pollutants. It's the same technology that is utilized in the Lennox Pure Aire system which I believe was on the market before the Aerus system was introduced. I had Pure Aire systems installed as part of each of the two HVAC systems in my previous home circa 2003.

In both the Aerus and Pure Aire systems, air is passed over a supported titanium dioxide catalyst (the honeycomb is a catalyst support and not a filter.) The catalyst is activated by ultraviolet (UV) light. Moisture in the air is converted to hydroxyl radicals which are strong oxidants that breakdown indoor pollutants.

The UV light and the TiO2 catalyst have finite life expectancies and need to be replaced periodically. I think Lennox recommends replacement of their components every two years. If the Aerus system was either not operating when your A/C was idle or the UV or catalyst were ineffective due to age, mold/mildew could certainly grow on the surfaces of the Aerus system.

Thank you! Well, the unit is always turned on, but over the summer we just had the fan on auto, so air was moving only when ac was pumping. If we kept the fan on low during the summer it could create too much humidity in the house. On the flip side, in the winter it was nice to run the fan on low 24/7 for that reason, it helped maintain good humidity in dry winter.

My thought was, in the several weeks where the ac stopped running bc it got cooler, and we weren’t running the fan, the moisture basically settled in the air scrubber and had the chance to get a little moldy.

I think you'll be better served by installing a wall-mounted unit versus an in-duct unit. That would provide continuous treatment irrespective of whether your are utilizing your HVAC system's air handler to circulate air. I don't know if Aerus makes one, but USA Nanocoat does https://usananocoat.com/shop/category/airocide/

Well…we have air purifiers in almost every room in the house (in addition to this in-duct scrubber)! I became overly cautious after all of this. Aerus may make some room specific purifiers but not sure about a wall mounted option. Ugh. This shouldn’t be this complicated!

There are a variety of methods for improving indoor air quality. The Aerus in-duct system you have works based on photochemical oxidation (PCO.) Most portable devices for conditioning a single room are mechanical filtering and/or adsorption devices-- not ones that utilize PCO. If you noticed an improvement after installing the Aerus unit and want to replicate its function with a wall-mounted unit, you'll need to select one that works based on PCO.