Guide to Pool Filters, Supplies, and Chemicals

A pool filter on the bottom of a pool.

Owning a swimming pool is great fun. Maintaining a pool correctly, however, can seem like an overwhelming task. With all the supplies and accessories available today for swimming pools, it is sometimes hard to decide what works and what doesn't. Taking care of your pool is easier if you understand the basics.

Swimming Pool Filters

The two most important areas to monitor and control in your pool are filtration and proper water balance. Knowing what works is important, and can save you unnecessary stress down the road.

There are three basic types of filtration systems, Each of these filters do the same thing — they filter the water of your pool. It is the varying degrees of effectiveness that each type offers that is critical.

  • Sand filters simply a filter that uses a specially graded sand as the medium. Water enters the filter through the diffuser, and contaminants and debris are trapped in the grains of sand in the filter housing. The pool water continues to flow through the filter, enters laterals in the base of the filter, and is returned to the pool. This type of filter will only trap contaminants that are 40 microns or larger in size.
  • The cartridge variety uses a paper-like cartridge as the filter medium. This type of filter presents from 300-500 square feet of medium to filter the pool water. It only requires cleaning and replacement once or twice per year. This makes for a real plus in the maintenance department, and it produces about the same water quality as a sand filter.
  • The diatomaceous earth (DE) variety uses diatomaceous earth as its medium. This substance is nothing more than sedimentary rock that contains silicate, which is a good filtering medium. Grids in the filter housing are coated with DE, and can filter out particles as small as five microns. This filter is backwashed for cleaning purposes, and then recharged with more DE powder. A slurry of DE is poured into the pool skimmer that recoats the grids in the filter housing through circulation of water in the pool. Because of their high filtration capabilities, DE filters will run at a higher pressure than a standard cartridge or sand filter, which can lead to inefficiency and flow loss in the pool.

Pool Cleaning Supplies

You will need nets to hand clean the surface of the pool, stiff bristle brushes and cleansers to clean the pool sides, and handy items like a pool water level checker. This device takes the worry out of maintaining the water level in your pool, and is simply setup by attaching a water hose and making a few simple connections. It checks the level of the water in your pool, and automatically keeps it topped off at a specific level. (This ensures that the water does not drop below a level that could cause damage to skimmers because of the pump running dry and creating an overload.)

Understanding Pool Water Chemicals

You must also know the basics of water chemistry, and know how to both sanitize your pool and maintain the correct pH balance of your pool. Although many different methods are used and advertised, the process is simple — you keep the water free of contaminants and maintain a pH level in the range of 7.2 - 7.8. A simple test strip is used to check pH balance. You simply place a white test strip into the pool water for a second, and compare the changed color of the test strip to a chart that indicates proper balance. This method, although simple to do, is very accurate. If the pH level is off, you add a pH decreaser or increaser (available at pool supply stores) until the pH level is in the proper range.

Sanitizing the pool is one of the most important aspects of having a pool, as it affects the health and safety of pool users. Chlorine or bromine is used in this process, and is added to the water on a regular schedule suggested by the pool manufacturer. Chlorine feeders are available that float in your pool and hold a chlorine tablet, making sanitization an easier task. Because chlorine loses its effectiveness over a period of time, a chemical called shocker is used to eliminate the old chlorine and any contaminants that the chlorine has eliminated. The pool is then recharged with chlorine. Bromine also sanitizes a swimming pool, and is preferred by people with sensitive skin, but is more expensive than chlorine.

Another consideration is the pool ozonator. This device produces ozone through an electrical process, which cleans the pool effectively through oxidization. The hard part is generating enough ozone in a larger pool. However, through the use of an ozonator, you can reduce the amount of pool chemicals used by as much as 60 percent, which is a large savings over the lifetime of a swimming pool.

Following a simple maintenance schedule will ensure that your pool will provide you with years of enjoyment. It is simply a matter of knowing what to do, and then making a schedule to do it.

Alden Smith is an award winning author and regular contributor to He writes on a variety of subjects, and excels in research.