Your high alk is from adding the buffers then. I would just make sure you do weekly water changes to get it down. I would do weekly 30% water changes to get the levels down to where they should be. With Oceanic, since it does have a low alk and high(er) calcium, I only add the buffer when I am putting water into the tank. Also, you do not want to use pH buffer. You want to use kH buffer, as that is what Oceanic is low in.