Best way to upgrade from 10g to 20g


I failed Kobayashi Maru
So I'm thinking about upgrading my 10g to a predrilled 20g (used from my lfs). I hate how sediment just sits on top of my water because of that stupid hob Rio skimmer. I don't feel like mod'ing it to point the suction towards the surface.

What's the fastest and best way to do this upgrade if I don't feel like cycling the 20g? I plan on putting the lr and sand into the 20g. Is there no safe way to do this? Would it have be just set up separately, taking maybe just 1 live rock and a cup of sand from the 10g?
Just move everything over. Reuse your sand, rock and water and you shouldn't have a problem. Moving a small tank is much more simple than moving a behemoth!!
But won't stirring up the sand cause problems? Or won't it matter, since I will be adding another 10g to the tank anyway and it will dillute it?
Not a huge hurry, but seeing as how I'm currently waiting for my 125 to finish its cycle (currently, ammonia is down, nitrites are over 5 ppm, and nitrates are starting to go up,so I'm near the end), I didn't want to have to wait as long w/ my smaller tank. Mainly because my 10g is just dirty, even with weekly water changes. I don't want my 2 fish to suffer.
Well, I'd just start the 20g and get it cycling. Either take rock from the 10g or go buy some new live rock. Whatever you're planing to do....

Seed it with some sand from the 10g tank. Put your new sand in the 20g and then take a few cups of sand from the 10g tank. Pour the sand out into the 20g tank in nice neat little piles. Don't slosh it around and don't spread it out. Pour it in a pile here and there. Leave it alone.

With live rock and some good sand from your 10g tank - I would think you'd be cycled in a month. I probably wouldn't load it down really fast. I'd try and transer a fish or two first and give it another month. Then add your corals.

It's really just personal choice. People have done both quick tank upgrades and slow tank upgrades.
I only have 2 fish in there -- 1 citron goby and 1 firefish. Plus 1 pistol shrimp, and 4 cucs....oh and a bunch'a mushrooms.

I thought if I add live rock and some live sand to seed it that I could safely do a transfer of just fish within a couple of days of setup? My 10g has a 3 inches of sand, so I know I'll stir up something if I dig some up.
I've done this before and just moving everything over and adding water worked great. I'm about to do the same thing in a couple weeks moving my 10g at work into a new drilled 20g. Good Luck!