Can you post a photo? It’s hard for me to determine what you are describing; detritus buildup, algae, cyano.
generally speaking, turning over the sand will help (not solve) with most problems. sleeper gobies are probably best for this,followed by other sand sifting gobies, followed by watchmen and pistol shrimp. I also find minimal value from sand sifting stars or Nassarius snails also.
that said; a photo will help.