Your parameters listed above are nearly spot on but wondering salinity and temperature parameters. I wouldn't chase the alk and calcium levels as they likely come down on their own thru corals use. It makes me think peppermint.
IF peppermint is what you are also thinking, bait trap to get it out and move to sump. I had my hammer garden decimated by my three peppermints. I waited a long time to ensure my hammers were unable to come back from peppermint eatings, before finally tossing leftovers in trash. Recently replaced eaten hammers.
To catch peppermints we used an icecap fish trap, but google fish traps as there are many DIY solutions including bottle you likely already have in your recycling/trash and just need to clean & cut-up.
