AH!!!! So THAT'S why PBs love to install cartridge filters! Thanks, Kelly!

They take on the nasty messy job of cleaning them for a fee! I never knew that--DE and Sand filters don't require such a service. That's clever thinking.

DE filters do need screens or fingers maintained, and some people pay for that once a season. Others do it themselves. Not being an expert on DE I don't know the details.

Sand filters only require back-washing, and that's no effort at all. There's no way I'd pay anyone (other than my kid's allowance) to do THAT for me!

But VERY few cart owners have mastered how to clean them easily...now I know that they pay the PB/Pool Service a fee to clean them!