You can just move everything over, but ditch the sand. Keep one cup of sand to seed the new sand. If you’re bringing fish over I’d add some Dr. Tim’s bacteria to help it along quickly so you don’t see a big ammonia spike. If ammonia is creeping up, do a water change to knock it down.
When you move the sand, you will very likely stir up all kinds of stuff which will cause at least a “mini cycle” in the current tank. From my own experience moving my tank, if you are able to, use new sand in the new tank. (*Right now, add as much extra filter media to the current tank as possible so you can move a lot over without upsetting the bacterial balance too much.). As soon as the new tank is filled with saltwater, move as much rock and seeded filter media from the current tank, move a cup or two of old sand, and add some bottled bacteria to both tanks (1/2 bottle per tank should be fine, just to be safe). Test the new tank water daily until it’s cycled(ghost feed a little if there’s no a/n/n reading at first). It shouldn’t take long to get there. This may be overkill for the size tank you’re moving, but if you have the time, it’s definitely better than losing any critters. Oh, and before you move said critters, make sure salinity, temp, and pH match; wouldn’t be the worst idea to remove 10 gallons and replace it with the old tank water to help acclimate. Good luck
The ideal way would be going to the new location and set up the new tank with the old media, a cup of sand, and a few pieces of rock. Test and match all the parameters. Then make the move after it settles in for a few weeks.
Doing it all in one day brings a lot of surprises and it always tanks much longer than anticipated. This is coming from a guy that changes tanks every few years. Believe me...be prepared for headaches.
One video that might help you plan it more cleverly. Go to 17:20 and you’ll quickly understand why I said ditch the sand.
Oh yeah, 5 months is fine. He can use it all.
