Alright sonny-Jim, you asked for some advice, here tis...
looks like the start of a diatom bloom which means your tank may be in for a hard cycle and ammonia spike (thats a bad thing if you have live fish in the tank). You may start to see the specks turn into larger blotches. Thats the diatoms.
Another thing, don't stir the sand by hand, you could release a ton of nitrogen into the tank that could be stored in the sand bed, that bad news for everyone in that tank, Get some sand sifters in there to do it naturally (sand stars, sand cukes or some sand crabs). SAND is in the name so its gotta be good
Keep an eye on on your water quality but I'd cut back on feeding a bit and reduce the number of fish. I'd start by getting rid of the Sgt. Majors as they can get big and really territorial (they're basically big damsel fish) and will bully your clowns to death.
thats my 2 cents