In my opinion going fallow and tearing the sand bed out will help you in two ways. One your rock will be past the four month mark maturing in the aquarium and you won't lose what you already have. Keep in mind what you already have is years of sitting in the ocean before KP harvested it! I agree with some of the others that trying to trap or use one of the methods, dry etc. to get the shrimp. Tearing the sand bed out this early in the tanks maturation shouldn't be a big deal and with little in the tank this shouldn't cause too many problems. Just keep in mind the first year with no sand bed is a pain in the butt while the tank ages in. That having been said I have zero tanks with a sand bed right now.
The fallow period works, but it only works if you adhere to a quarantine protocol afterwards. Are there a few isolated incidents of it failing, sure. I am of the mindset however that this failure is not due to the fallow period itself failing but the aquarist failing to adhere to the protocols to keep the tank disease free. If an aquarist leave the tank fallow for 76 days, and they have zero cross contamination the moment they put anything wet in there that hasn't followed a 76 day quarantine protocol, earlier for fish that are prophylactically treated to wipe out diseases, the aquarist renders the whole thing moot. The second you place one of your corals back in without treating it somehow you destroy anything you've done to eradicate the disease. Others may know more about this than I do, but the only way I know to treat coral for ich and velvet is the fallow period. Yes, ich can adhere itself in its sedentary stage to your corals.
Excellent spreadsheet!! Thank you for having so much detail! I'm looking at some of the swings in specific gravity and alkalinity and wincing. I'm hoping that the several days in between some of the testing is the time frame taken to make some of the changes. Acros like rock solid parameters your alk should not swing like that while trying to keep them. I would suggest adding an ATO to your setup to keep the SG stable as well. I'm thinking those swings are what killed the acros. When keeping them test your alkalinity daily, a Hanna checker is a wise investment to cut down on the headache of doing this.
If you are dead set on tearing it down, wiping out the rock and starting over do not use copper in the DT or on the rock, if you do you take the chance of it being absorbed by the rock, silicone in the aquarium etc, and leaching back out over time. The only sure way to rid the rock of disease and pests without using the animals biology against it is bleach. At this point you will be killing everything and starting at zero, like the day zero before KP put it in the ocean. I did this to make completely sure I killed off bubble algae, aptasia and vermatiid snails that I introduced when I was impatient. Now I just hit the one month mark and I haven't even turned the lights on yet. You will be setting yourself way back and possibly have a tank too sterile for the montis and stylo until it ages in.
Whatever you decide to do, good luck, I'll stop hammering you on the fallow period. The last thing I'll state before that is to take the advice of those that have come before you and made the mistakes already. You are stating that your intuition is telling you to tear down the tank, kill off everything in and on the rock and start over. My intuition based on being in the hobby since 1990 and making many a mistake, is you are headed down the road to more heartache. Again, good luck!!
