Swimming pools blog

Hi group, I have a 18′x30′inground pool, vinyl liner with hayward sand
filter and 1hp pump. Last fall I notice the water going into the
skimmer would slow down.After backwashing and cleaning filter would be
fine for a couple of hours, then it just began to slow no matter what I
did. The old filter had leaks, so I had it replaced it a couple of days
ago. When I turn on the pump the water goes thur fairly quit but slowed
down again. The guy who put the filter in said this was normal. I know
the water used to run in faster. Do I have a clog in that line and if
so how do I flush it out? thanks for the help.