I transferred everything, sand LR and water from my 20 long to a 24 nano cube. First I pumped all but one inch of water from one tank to the other, second I used a new dustpan and scooped the sand out of the 20 and placed it into the 24. Topped off the 24 with aged salt mix. There was a small spike and I left my tank "cycle" for 4 weeks to make sure, I had a small diatom bloom, saw all kinds of "critters" in the sand and on the glass. My tank did not go through a big cycle as it would have certainly killed the critters. I did not rinse anything because I wanted to take all of the bacteria. When I did this change I also put in some old live sand. Now this sand has been in a 5 gal bucket in my garage for almost 2 yrs. there was probobly 3 inches in the bucket. everything was fine in my tank after 4 weeks. There may be holes in this story so ask away.