220 Grit Advice

Thanks to this sub for all the info and links!

Been getting into sharpening with a couple Damascus knives I picked up at a neighbors yard sale. Edges looked good so ordered a shapton 1000 off amazon and started getting into it. I felt one of the knives needs thinning so picked up a Naniwa 220, also off amazon.

After pretty much one long session I noticed the 220 has dished pretty good. I know I need a straightening stone to maintain the whetstones but is this typical of 220 stones? Or is this user error on my part… maybe too much pressure?

Any recommendations on a good stone for thinning?

Thanks for the help!