I have kept over 50 different species of salamanders and the best way to keep ambystomids, such as Blue Spotteds or Jeffersons is as follows.
I use plastic sweater boxes with holes punched in the sides but a 5 or 10 gallon tank will work just the same, maybe with plastic over the lid (and make sure it has a locking lid) to prevent drying too quickly. The substrate should be 2-3 inches of forest floor soil mixed with wood rot (from actual rotting logs in the woods). Then lay down a few pieces of wood or bark, also from the woods. Then scatter a few leaves on top of that. Feel free to plant some moss or grass over in a corner. If there are insects such as pill or sow bugs in the soil, all the better they help break things down. Throw a few worms in to keep the soil aerated and clean.
Mist it down with dechlorinated tap or spring water twice a day. In general the soil should remain consistent with that of moist woodland soil, not wet mud, i.e. the exposed soil should be fairly dry and the soil under the bark or wood should be moist. If it becomes too moist the natural cycle of the mini environment will not break down toxins properly and bacteria and fungus may fester. Most salamanders I have found in the wild I have found in fairly dry conditions, in fact if the substrate is kept on the drier end the salamander will actually form a "cacoon" of skin over it which helps it retain moisture and also keeps out potential skin infections.
This natural setup acts much in the same way an undergravel filter works in a fish tank. The natural biological organisms in the soil break down waste and keep everything balanced. Toss in a few earthworms (leaf or dill worms from the bait shop, or similar sized worms from the woods) a couple times a week which should make up a bulk of the diet. Crickets, mealworms, waxworms, sow bugs, spiders, and whatever other little crawlies you find you can toss in as well. Generally if you add these food items at night and mist the tank just before you shut off the lights the salamander will come out and hunt its food. Monitor the salamanders weight and whether or not the food items are being consumed. Lighting should be non existant or minimal, in that they are fossorial and nocturnal, allowing natural room lighting from windows will work fine (but not direct sunlight). Also very important, DO NOT keep them in an environment that gets much more than 70 degrees, they like to be kept in the mid 60s range. So a basemant or closet would be ideal.
I use this setup in a sweater box for 5 Blue Spotted Salamanders, 2 Marbled salamanders, a Gray Treefrog, and 2 Fowler's Toads and they are thriving.
Any other questions just ask.
Dave