Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I would use the gravel from the 10 gallon as an accent on top of the EC. Not an evenly spread out layer, but in drifts and patches.
Here is how I would do this:
The top layer of the gravel has a very high population of nitrifying bacteria (If the 10 gallon has livestock).
Skim that top layer off and save it in a humid place (perhaps in a separate bucket with a little tank water).
Set up the new tank, include the bacteria rich gravel where it will look nice, sort of like a stream bed, on top of the EC. Perhaps add some larger rocks. Plant it, being careful not to bury the beneficial bacteria.
Alternate: If you want the gravel look in the new tank: Use all the gravel from the 10 gallon to top off the EC, but start with the gravel from the lower parts of the 10 gallon (probably lower in bacteria) and make sure the bacteria rich gravel is well scattered on the top.