Pretreating for pests has nothing to do with how you take care of your system or what equipment you use. If you put corals from the LFS, an online retailer or even a local reefer then you will eventually get one pest or another. Sometimes it's a minor problem that requires a simple treatment and other times it will result in a total loss. After putting so much time and money in your tank, can you really not justify taking some minor precautions to avoid a major problem?
Red bugs, flatworms, AEFW's, sundial snails, pyramid snails, isopods, nudibranchs and a host of other unwanted pests are all lurking out there and the odds are against you.