Keep your filter clean!
Filtration is the first line of defense in keeping pool or spa water clean. Think about it this way: Without a properly working filter, there is no amount of chemical treatment that will keep the water clear. Unless water is properly filtered to remove solids the water cannot take on a clean appearance regardless of how diligent you are in chemical management.
Check out GLB® Filter Cleanse. This multi-purpose granular formulation cleans and unclogs all types of swimming pool filters of grease, oils and scale with a combination of acids and detergents. Its unique chemistry will gradually change from red to yellow as it cleans.