Using the plastic does help. It still creates a small sand storm, but it clears up in a day or two.
As for the sandstorm, I'm guessing that Bang is suggestiong the sandstorm so that the finer particles are on top and the larger pieces stay near the bottom. (Ultimately causing areas for anerobic bacteria to thrive and cause denitrification - but that's in a DSB so it wouldn't apply here .. I digress)
Now that I made that assumption on Bang's advice, the thing is, over time with sand sifting, the finer sand will still rise to the top layer. Just like if you put sand under CC, eventually the sand will make it's way to the top layer, and the CC will 'sink' to the bottom.
How did I do BANG?