I'll throw in those gel packs every so often to help with that.
Check those, too since a broken seal on your vac container will cause them to become saturated (and ineffective) fairly quickly, and re-sealing the container with the saturated pack left in would not be ideal.
You can weigh your desiccant to tell whether it's saturated or not. If it's been sitting around for a few days or so it's probably saturated, so record it's "full" weight at that point then dry it out in the oven and weigh it again for it's "empty" weight. After that you can check 'em real quick and easy.
That level of detail is really only important when intended to store them longer than 2-3 months or so (esp. in Winter), unless you live somewhere with excessive humidity.