For those of you that have cartridge filters make sure you clean then at the beginning of the season and then mid season. You need to use filter cleanse products to get the oils to release from the fiber paper.
Below are some filters that were so clogged that they were compromising the water returning to the pool. Had the home owner not alerted us that they were have circulation problems they could have built up so much pressure the water would have blown a line somewhere in the equipment or worse. We had a used set we put in their filter and are ordering new filters however we will post pictures of these so that the clients can have them for spares.