I have two Bionaire humidifiers that were given to me recently. They had been used before. When I got them, I dismantled them to clean them completely before using them and I found that there were large calfification deposits inside the units. I cleaned the calcium build-ups as much as possible but some has come back. I keep cleaning and it keeps coming back! What causes this build-up and is there an effective way to get rid of it for good? I use well water which has been tested as virtually mineral free so I don't understand why it keeps coming back. Help will be appreciated!:D

It is in the water if it is a mineral/calcium deposit. Lime Away works well to remove deposits.

I have never seen well water that was calcium free.

It could also be some other type material. Best to send out a sample for testing so you know what you are dealing with.

In the future try to use either distilled water that is store bought or purified water that is store bought. This will eliminate the calcium build up should it continue at your house.