Sand getting past my cartridge filter

I've got a clean and clear plus 420. 1 1/2 uprated whisperflo on a 18,000 gallon pool. This is a new pool a year and a half ago. I bought an oversized filter wanting to make sure I kept the pool clean. Every morning I get up and the pool is dirty. So I have tried turning the pump off and no dirt in the pool (except windy days). I use a robotic cleaner after the pump is done. I have cleaned the filter many times. When the pool was put in a little cement got in the pool. Manually vacumed it up.

I'm extremely frustrated with the filter. I have added a little DE to the filter per filter manual. Maybe I put a hole in the filter with the cement pieces. I'm thinking about buying new catridges, but I don't want to put that money into it only to have the same thing. What should I do?

I don't have the same brand cartridge filter, I have a HAyward Xtream. It sounds like your element has a hole in it. You'll have to inspect it. You shouldn't be getting any sand or sediment past the filter when vacuming. When you put DE in, did any come out of the return? If not, then sand should not be coming out either.