Foo - Cold humidifier: preventing bacteria/odor.

I have a cold air humidifer. That is, it relies solely on the nature of water evaporation to humidify -- it doesn't emit a mist. In terms of humidifying, it works well. The problem is that, after two days or so of the water sitting in the open tank, it begins to smell. After 3 days it's not pleasant. I'm able to prevent the smell by changing water on a daily basis, but I don't think I should have to.

Currently I add a drop of dish soap to the water; this acts as a surfactant, letting the water evaporate more easily. I would have thought this would ****** the growth of odor-causing bacteria. Can anybody suggest an additive that would prevent growth of bacteria and is still safe to be in contact with? My guess is that the dish soap doesn't evaporate, so I probably don't come in contact anyway.

My first thought is a small amount of bleach. Maybe 1/4 cup per gallon of water or so. Enough to keep bacteria from growing, but not enough to smell.

Taking care of humidifiers correctly is a ton of work. I am running three at home now and each is a different type.

You DO need to change the water every day. In our house, though, we go through one or two tanks of water a day, so that isn't an issue, but occasionally the water will sit in the tank for a day or two and it gets bad after sitting for just one day.

You also need to CLEAN the unit at least weekly: clean the tank with bleach/water mix; clean the unit with vinegar. In each case, let them sit for about 20 minutes, swishing ever few minutes. Do not let the two mix, though, or you will kill yourself (I had a serious scare not too long ago when I let the tank with bleach sit on top of the unit with vinegar and the solutions mixed).

Also, I find that with wick filter units I have to change the filter more often than recommended, too. I also have two filterless units which are great but you have to be much more careful with the speed/moisture settings than with the wick unit, since the wick regulates itself and the filterless will keep going unless you tell them to stop.

I switched to a warm humidifier for this reason. I could never keep my cold one clean.
It also keeps my bedroom warmer.

Thanks for the replies. The unit I have is the Venta Airwasher.
http://applianceparts.files.wordpress.com/2009/06/venta-airwasher-lw14.jpg

Am I correct that the bleach wouldn't evaporate if I added it to the water? I clean the tank weekly, but I just scrub it with soapy water and a nylon brush. I'll try your method next time.

The cold humidifier is optimal to me because it doesn't require filters and sort of "self regulates" the humidity; warm ones can turn a room into a rain forest. This unit also uses 1/3 of the energy required by a conventional, steam based humidifier.

If it is filterless, is it ultrasonic?

ETA: Ohhhh, it's the spinning disk kind. From the research I did, those are smelly, bacteria-ridden types of humidifiers. :)

If you want filterless and cold, look for an ultrasonic type. But then you have the possible white-dust issue, which Venta claims as a plus for their disk version, but disks have their own issues.

The best ever is still a wick type, but wicks are expensive and can get moldy.

warm ones can turn a room into a rain forest.

Like going to Brazil, but cheaper? I have to get one of these.

Mine doesn't. I have a small warm humidifier that I use while sleeping. No issues at all.
If I had the money I think a whole house humidifier would be the bomb.

You don't need to use chemicals to beat bacteria or fungi. Fungi cant live in alkaline environments so if you add some Bicarbonate of Soda to the water you will kill any fungi. You could also acidify the water by adding some vinegar if that doesn't work.

Anthony

Thanks AnthonyG, that's exactly the response I was looking for. Somebody told me salt water will reduce bacteria growth, but I think vinegar or baking soda sounds more promising.

If you want filterless and cold, look for an ultrasonic type. But then you have the possible white-dust issue, which Venta claims as a plus for their disk version, but disks have their own issues.



My parents use an ultrasonic humidifier from Venta, but it still requires replacing a cartridge. Failure to do so results in white dust; my guess is the cartridge is supposed to filter the water to prevent that. They fill the tank with filtered water to prolong the cartridge's life.