I've watched and enjoyed each of your lafishguys videos dozens of times.
Just my two cents, but I think that sandbed of yours is the source of a lot of your problems. I believe a tank should either have a true deep sandbed (i.e., the right sand depth/grainsize/sandsifters and leave it undisturbed to do its thing) or have just enough sand for aesthetics.
That constant vacuuming and churning of that thick sandbed is just constantly burying detritus and creating a mess.
My first reef tank was a 75g that was heavily stocked and fed generously. I only had about 1" of sand in there, but when I eventually cleaned it out, the sand was utterly disgusting.
Have you tried pulling-out some of that sand (and rock), putting it in a separate container (with no filtration), and testing it to see how much nitrates/phosphates is leaching?
Best of luck and continued success with your tank.