I'm in a 2-season country, dry and wet seasons. I live in a cold place, with temperature averaging to 19 degrees on the wet season and about 25 on dry season.

Last wet season, after a couple of storms, I noticed a couple of lenses has molds in the form of tiny "spider-web like" spots on glass surfaces, (are those even molds?). I was stupid in that I always left my lenses and camera in my work table, without any kind of protection.

I got myself a dry box for my lenses. It is not anything fancy or expensive: just about 150USD generic drybox about 2 feet tall. The thing is, I decided to initially turn it on for 24/7. After about a month, the electric bill went up significantly.

Considering that it's the dry season already and it's mostly sunny, do I need to turn it on 24/7? Do I need to turn it on often when it's rainy and humid and all that stuff?

I have no knowledge of humidity control, mold control for equipment or something like that so any help would be pretty much appreciated.


One option would be to look at the relative humidity(RH) that you are setting your dry box at. Usually you want it in the 40-45% range for camera equipment, anything lower and you are just wasting energy. I would make sure you are in this range.

  • the drybox is automatically setting the value, even if I adjust it (does it really work that way?) so if it is not in that range, or it is in the higher range, I can turn it off? – Ygam Nov 26 '12 at 2:51
  • I would expect (never having used a dry box) that it has an electronic hygrometer (humidity meter) that works exactly like the one on the humidifier I run in my too-dry house in the winter, only set the opposite way — in either case to run on only when a threshold has been crossed. If it's not designed to turn off automatically when not needed, you should get a better model. – mattdm Nov 26 '12 at 4:55

I don't know what is and isn't good enough, but if I were concerned about it (and maybe I should be, because I live in Alabama where it gets nice and humid) I might throw a bunch of silica gel in with my equipment. I have some lens cases that came with them (presumably more for the case's protection than the lens) and I keep them in there. $5 in gel packs seems a lot cheaper than an out of control electric bill.

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