• Circulation - The more the water moves, the harder it is for problems to take hold. Additionally, properly circulated water insures that chemicals are properly mixed throughout the pool.  The best time to circulate  the water is during the day, for 10 hours or more.  The more your water is in motion the harder it is for bacteria and algae to take hold
• Filtration - The filter is  on of the most important pieces of equipment.  Filtered water removes insoluble waste particles that can cloud the water and compete with bacteria and algae for the sanitizers attention. Generally a filter should be backwashed when the water pressure in the filter reaches 8 to 10 psi above normal  (check manufacture's guidelines). 
• Cleaning - Some swimming pools have areas with little or no circulation. Vacuuming and brushing debris in the pool and on the surfaces prevent the growth of bigger problems, making it easier to keep the water clean. Routine use of a skimmer net is helpful in removing floating debris to prevent it from settling to the bottom of the pool.
• Chemistry - Adding the proper amount of the right products at the right time insures that the water stays clear, clean and healthy.  Balancing the water will protect the pools equipment and pool surfaces.  Unbalanced water can permanently damage both.
• Testing - By measuring critical water factors, you can make sure the water is balanced and an adequate sanitizer level is being maintained.  Most important are the pH and the level of active sanitizer.  

Paying attention to these five keys will guarantee the beautiful water you expect. It should also be understood that poor filtration or inadequate circulation cannot be overcome by adding more chemicals. Numerous water problems are related to poor or inadequate filtration and/or circulation.