What is a good way to remove a stubborn kitchen sink aerator?

I am trying to install a water filter on my kitchen sink and I cannot get the aerator off. Anyone have any tips?

Grab it with a pair of channel lock pliers and turn clockwise

if you are not going to use it anymore, use pliers. ( it will scratch it though) If you want to keep it, maybe the rubber jar opener thing would work.

Spray liquid wrench or wd40 on it to breakdown any calcium that has built up on the threads. After a few minutes use a channel lock or vise grip pliers to remove it. Righty tighty, lefty loosie. You may also have an aerator that has an internal expansion screw. Look under the aerator to see if there is a screw head or slot for a screwdriver that when backed off releases the pressure on the retaining spring.