I am thinking it is filter is clogged if you got the air out of the line. You had just cleaned the pool and if it had been shocked or had sand or things too small to get caught in the basket, they are in your filter. Does backwashing help? I have only had DE filters or Cartridge filters and both eventually get clogged and backwashing doesn't help and you have to open them up and wash down the grids in the DE filter and the Cartridge in the Cartridge filter. I do not know how you clean a sand filter but assume if has to be periodically opened and cleaned, I am sure someone here can address that.
Sounds like a Honey do issue to me, when was the last time he opened up and cleaned the filter?