How to use a vaporizer safely when you have BE and MAC

A couple of months back I shared my dilemma about needing to use a humidifier for my eye condition. Scoop kindly informed me that the safest choice is a warm steam vaporizer that boils water and so kills bacteria. I bought one, but haven't used it yet because I have been trying to avoid breathing in anything aerosolized or adding to my daily cleaning processes. Instead, I have avoided turning on my heat and have added another layer of clothing. This has worked well so far, however, now that the temps are starting to fall, I notice that the humidity in my house is lowering and my eyes are starting to complain.
Time to bite the bullet and pull out the vaporizer. My understanding from what I have read (don't remember where now) is that it is important to clean out the vaporizer with bleach after every use. My question is: What do I do if I use the vaporizer not just while sleeping at night, but all during the day? Do I have to clean it each time I add water, or can I add water regularly during the day and clean it once a day? I'm trying to keep things simple, but I want to do it safely. Many thanks,