The unit can sit unused; we do strongly suggest storing it in a dark place. Using a black plastic contractor bag works well.
You can discard some of the first water that is produced as an added safely measure, Although I have never heard of any problems resulting from a properly stored unit.
We do make a Silicate Blaster DI filter, the standard DI does remove silicates, but if you have an excess of silicates the Silicate Blaster filter will last longer.