Apparatus for operating a filter arrangement

An apparatus for operating a filter system of a swimming pool in proportion to the degree of water contamination, said apparatus comprising:

• overflow tank means for receiving water from the swimming pool as a function of the number of persons entering into the swimming pool;
• filter means;
• variable output pump means;
• pipe means for interconnecting the swimming pool, the overflow tank means, the variable output pump means and the filter means in a substantially closed loop;
• sensor means for detecting changes in the level of water within the overflow tank means in response to the number of persons in the swimming pool and for generating a first value representative thereof;
• computer means comprising memory means for storing values representative of at least one parameter selected from the group consisting of:
• natural loss per unit of time, fresh water added, and water loss due to spillage
• means for processing the first value and the memory stored values to derive a second value representative of the degree of water contamination;
• and
• means for controlling the output of the variable output pump means in response to the second signal.