Reduck
Because I can....
Gonna take about 1/3 to 1/2 of the sand out of my 14G bio-cube along with all of the rock and move it into the new tank so it will be easily cycled and I can move the fish over quickly. Gonna turn my 14g biocube into a Quarantine tank since I will finally be able to get more fish. Was already over my limit in the 14g with 2 clownfish.
Just use a cup of the sand. Don't need it all, and as biz said, you are moving a lot of junk with thr entire bed. LR is ok, as long as it doesn't have any bad hitchhikers aboard. It will only worsen in the 40 durin the cycle.
Good luck!