If you want to remove a lot of bass relatively quickly, have the pond shocked right as the bass are spawning. Shock at night and don't fertilize the pond that year before shocking because you want to be able to see thru the water.
On fertilizing, I would try to keep the water clarity between 18"-36" due to the phytoplankton bloom. 12" clarity is a bit too dense and can limit O2 availability during the warmest part of the summer.
Are you aerating the pond?
I would think about getting a truck in there to add a bunch more Ag lime to the pond and surrounding area. The alkalinity reading is OK, but on the low side to what we are accustomed to seeing up here. I'd like to see you slightly ahead of the curve rather than you to play catch up if it drops too much more.
