For starters, never dose anything into your tank that you can't test for. Unless it is one of the better quality tests, aka anything api doesn't count, you shouldn't trust the reading. You should maintain regular 10% water changes to ensure your parameters are not out of whack due to said dosing, as fluctuations in alk
can be quite harmful to corals.
Now, as to your question of the bleached coral, the what appears to be a fading hammer coral is most def in such a condition.
For starters, it is in the shade. Move it out into the light on the sandbed.
What size is the tank? What is the lighting over the tank...and be specific as without knowing either the type of unit, how many bulbs, or how many watts...so on it is hard to tell if the lighting is even suitable to keep photosynthetic creatures! Sadly, there are units out there marketed to be able to do such and it is the opposite in nature.