Adding new sand to old
As the title says, a very quick question: I have some CaribSea Super Naturals sand in my tank currently; it's been in for at least 7 years with no issues, but I'd like to make it a little deeper, especially in one back corner.
Would there be any issues you can foresee with just adding more of the same from a new bag on top of the old? I'd be concerned about trapping any mulm in there, but then my sandbed is really not very deep anyway so this might be a nonissue. It's currently only an inch deep at the deepest points, I'd want to go up to ~2" or a little more if that wouldn't be an issue, to give my swords more rooting area.
My other thought would be to siphon the sand out from this corner - behind a driftwood retaining wall - and mix the old into the new before adding it back there.
The majority of the sandbed I'd not be disturbing, so I think from a bacteria/cycle perspective it shouldn't pose any problems.