Any suggestions on how to clean pumps/skimmers effectively? Just tap water and scrub? I figure I should break my main return pump down and clean it when I have the sump apart.
Search for "how to clean protein skimmer" or the same for return water pump. Parts without metal get soaked in a white vinegar solution, pure vinegar works faster. For large surfaces spray it, or cover them by paper towels with vinegar and cover by plastic sheet to reduce smell and evaporation, then scrub with a brush. Rinse well.
For parts with metal, soaking and scrubbing with impeller brush and larger stiff brushes, finally some mild disinfection with weak hydrogen peroxide.
Now about main procedure, from my experience with resetting tanks:
You have fish there, I would gradually change situation without tearing tank up. Too high probability of breaking balance and getting ammonia and nitrites.
Compare alkalinity of your new saltwater with alkalinity in the tank. Drastic difference, 3-4 dKH, with tied to it increase in pH, at once, without acclimation, can noticeably affect tank inhabitants.
Small frequent cleanings with average water changes, not increasing alkalinity more than 2-3 dKH, should be safer. Rock can be removed, not all at once, plucked and scrubbed in the old saltwater, removed at water changes. Spraying it with peroxide also could be done, but for small parts of the rock, nit all at once, or you can get ammonia in the tank from the large amount of decaying organics.
In the time between water changes, keep filter socks clean, maintain alkalinity a bit closer to the alkalinity of a new saltwater by dosing. When doing water changes, siphon out with hose what you scrubbed from walls or rocks and accumulated detritus. After starting siphoning sand bed risk increases, do it in small parts and watch for ammonia spike after that, keep Seachem Prime ready for temporarily binding it. Change activated carbon frequently.
This way would be more work, but no agitated animals.
