I think the sponges do a better job than adding water containers. I just put mine right under the holes in the top of the bator and use a straw attached to a small funnel to add warm water to them as needed. It works great and I have no trouble getting my humidity up and keeping it there. Also, with using the straw/funnel thing, I don't have to open the bator and lose humidity or heat - a real no-no in those last few days.
My update: We had a power outage the other day and I was at work, so I couldn't do anything to insulate my bator and help hold the heat in. When I got home, the power was back on, but the probe temp in my bator was only at 97.something, so I'm not sure how low it really got. I know that the power was only out for a few hours, so I'm not terribly worried. I've been very busy, so I haven't been tempted to candle, but I think I'm going to today, just to satisfy my curiosity. Actually, maybe I'll go do that right now. . .
My update: We had a power outage the other day and I was at work, so I couldn't do anything to insulate my bator and help hold the heat in. When I got home, the power was back on, but the probe temp in my bator was only at 97.something, so I'm not sure how low it really got. I know that the power was only out for a few hours, so I'm not terribly worried. I've been very busy, so I haven't been tempted to candle, but I think I'm going to today, just to satisfy my curiosity. Actually, maybe I'll go do that right now. . .