That is an excellent question. I myself have fallen victim to the reusing sand trick. You can re use sand, but it sounds like you would like to keep the 95g tank, so why mess with a good thing. Moving sand exposes it to air, and stirs up a bunch of trapped organics, this can cause many problems in a new tank. I would buy new sand for the 29g and seed it with a cup or two of your old sand from the 95g. When moving the old (seed) sand try and make sure that the sand is always in saltwater, scoop in a cup with less sand than total volume so the rest is water, and then dump into a filled aquarium (again submerged in saltwater). I like to dig a small hole first and then fill and cover, but this might just be voodoo. You can use old water if you like but this won't speed up your cycle in any significant way, so why not start off with fresh water?
So now we have brand new sand and water, so what about rock? This is where you can get tricky, a new tank is a great place to cycle uncured live rock but this does add to the time (and a smell) before you can add livestock. So this one is personal preference. You could use 30% old water and move existing rock from the 95g to the new tank, this would result in a much shorter cycle but you now have to replace the rock you took from the 95g with cycled/cured LR. My opinion is to start fresh and cure some rock, purchase cured rock or go with dryrock (I know some here think this is a dirty word). Then just like you seeded the sand you can seed the new rock with a bit of LR from your 95g.
Any way you go about it the same rules apply, you need to let the tank cycle before you add livestock, regardless of what bacterial supplementation or seeding you use, and your test kit is only opinion on cycle time I would listen to.