Diatom or Detritus?

[Cubano32]

Hey guys so I keep having this issue in my sump and on my live rock not sure what's causing the issue and what it is exactly..on the live rock it will go away I see my snails clean it cause they leave a path where they have been...anyone got any suggestions

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[Coral Man]

Little bit of both, detritus sticking to the algae since lower flow. I’ve got a display fuge so I often clean the viewable side.