The water is clean and there are no problems with debris so I think something else is happening. Just to make things clear about my situation I would like to explain that my valve on my sand filter leaks to backwash pipe when the valve is in the filter position. I installed a gate valve to stop the leaking but did not fix the spider valve at the time since the pool company said that the gasket on my multiport valve was not replaceable in my sand filter. I don't know if this could be related to my issue now or not but my flow rate decreases sooner than it use to and I find myself backwashing more often it seems. The sand filter is a Hayward S220T. the sand to my knowledge has never been changed and it would be 4 or 5 years in service. I don't know if changing the sand would be advisable or not. Any suggestions would be appreciated. Thanks Jim