The symptoms would be that someone or all who use the pool would come down with diarrhea. It is passed on from person to person. One who has experienced or has diarrhea should not use the pool. Bring the chloine levels to break-strength levels -- 10.0 ppm and keep everyone out of the pool for at least 24 to 36 hrs. The filter should be opened, if D.E. or Cartridge, filter elements should be hosed off and chlorine washed, the internal parts of the tank and pump should be sanitized as well as the plumbing (as best you can). Assemble the filter tank without the elements and after starting circulation dispense chlorine directly into the skimmer to flush all lines. Then you may reassemble the elements in the filter and charge the D.E. filter with proper amount of DE. Run the system 24/7. When the chlorine level is down to about 5.0 ppm you may resume normal operation and use of the pool. With sand filter - back wash and rinse - then flush as above without disassembling the filter.
The person or child with diarrhea should be kept out of the pool until all symptoms of the ailment is gone.
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