I use a cool mist one but only with reverse osmosis or distilled water. It must be sanitized with bleach every week, but that probably should be done on any type of humidifier.
I disagree with the pebble tray idea - physics says it won't work well. Read this.
Last winter when I was experimenting with my little grow tent I put pebble trays (2) on heat mats and checked the humidity in the tent some hours later. It got up to 90% with a temp of 78°f. I would say they worked in my case. See the thread here Moving to a grow tent
Last edited by Dusty Ol' Man; 09-25-2021 at 10:00 PM..