Since then, once the RH gets down to around 63% I'll add 20-30ml of water and it will come back to 65%. I generally have to add water every three months or so. They're pretty trouble free and don't require much attention at all.
This is exactly what I do. Before finally making the switch to Kitty Litter, I ready every internet post, every guide, asked all sorts of questions, the whole nine yards.
Once I went out and bought them I realize that I read WAY too much into all those guides. Sure, if you want to be anal about anything go right ahead. If your tolorances are small, you'll benefit from this (plus it's kind of fun to tweak stuff). But honestly, fill a mesh bag full of beads and place them in your humidor. Monitor every 6-8 hours as your RH drops. Add Distilled Water each time you check (~3-4tbsp) until your RH starts going back up. Stop adding once you get desired RH. Every 3 months or so add a few more tbsps. It's honestly that easy (and cheap!)
EDIT: I just wanted to point out that I don't mean to downplay the Heartfelt beads or any others. I know they are brothers on this forum and their products are more that just "silicone balls." They take care of all that "zeroing" for you. The Kitty litter is just cheap and you do the work yourself.