Regular cleaning of your pool filter is extremely important in order to maintain clean, clear pool water. Over time, the filter cartridges will become clogged with debris which increases the pressure within the filter and reduces the effective circulation of water back to the pool. Cartridges typically last anywhere from 3-5 years before they need to be replaced.
Be aware that the most dangerous part of pool care is proper handling of the filtration system. Filters are under pressure, and have been known to explode and cause serious injury, and even death.