IMHE, you will have a huge amount of dead/dying flesh in your tank, leading in a such quantities to the tank crash.
pH and alkalinity: application of kalkwasser paste, in small quantities (max 0.5 cubic cm - didn't tried more), onto the mouth, left without flow for 15 min, then removed by big pipette or siphoning, didn't made drastic changes. I didn't test before and after, just judging by corals, feather dusters and the fish reaction.
Tried the hot vinegar once - it killed few heads of blastomussa and had to make a partial water change.
Read somewhere, that for removing a small patch of inkillable turf algae, could be used sealing it by CA glue, like super glue.