One of the most important steps to keeping a deck from rotting is to clean it with deck cleaner once a year. To save money on deck cleaner make your own. This guide contains deck cleaner recipes.
Here is a homemade recipe for cleaning your deck. This works as well as the store-bought cleaners and is far more thrifty.
Mix one part chlorine bleach with four parts water. To each gallon, add one tablespoon of TSP (trisodium phosphate) which is sold at paint stores or the big box home improvement stores or enough TSP to make it sudsy. Do not use any cleaner with it that contains ammonia (this can emit a dangerous gas). Apply with brush, let set 10 minutes, and then rinse.