Reefnewb. I am fully understanding your level of frustration with the Dinos. As a last ditch effort reboot the tank. Pukani is great rock and unobtainable now. Have you done a full rip clean? All rocks out, scrubbed and replaced? All sand out and rinsed totally clean?
If you do restart, you can use your old rock. I would soak in bleach solution, rinse well. Then I would soak In a vinegar solution. This will kill then dissolve organic, and dissolve any calcified crap. I’m sorry you have battled this for five years. The deep blue 80 is a great size tank.