Unless you have a legitimate DSB in your tank (which is very rare) that shouldn’t be disturbed, not gravel vacuuming your sandbed is like not vacuuming your carpet. That’s where the solid waste and detritus accumulate to continue to decompose and acidify your water. Most people overfeed and that’s just fine, but removing detritus that’s not really beneficial to anything in your tank gives you less acidification for a more stable pH, less problems with nuisance algae or Cyanobacterias and a better looking reef overall. I suggest that any time you change water, it should be through the gravel vac. A person would not hold their vacuum in the air and expect it to result in a cleaner house. Also, you should be using a Turkey baster or whatever item of your choice to blow detritus off the rocks. There’s your coral and clean up crew food right there. When you read about the clean up crew or invertebrates that feed on “bacterial films” they’re also talking about the bacterial clumps and decaying food and waste that accumulates there.Another vote for conches.
Have 2 tiger conches and they seem to eat just about anything, even stuff like green cyano that most of the rest of my CUC ignored. Past tense, as they ate it all.