So, as of today, I've:
Now, I sit back and wait. Ammonia has remained at ~4 for a week now, although it did dip to 2 at one point, then climbed again, so I'm assuming the dead CUC was pushing it back up again.
- Turned off the skimmer completely for a week (didn't realize that was a thing with bacteria additives)
- Filtered with carbon for a week ahead of time (turned off now)
- Pumped 15 gallons (20%) out of the tank
- Carefully sifted about 15 dead snails out of the sand bed
- Added 15 gallons of fresh RODI saltwater, at the proper temp
- Waited a couple of hours for everything to stabilize
- Slowly poured a large (75 gallon size) bottle of BIO-Spira into the baffles in the sump, through the plastic bio balls and the ceramic rings
Fingers crossed...
In the meantime, I've ordered some pure ammonia and a smaller bottle of bio-spira, and I'm going to empty out the QT and do a few experiments starting from a fresh tank to try to get a handle on all of this without the weirdness of the possibly dead live rock, the used sand and the dead CUC.
I know it's very tempting to constantly be testing and tweaking but sometimes the best thing for your tank is to just stay consistent with one plan and let the tank do its thing for a couple weeks. Patience is key.