Here are a few tips to make the most of your terrarium.
Wash the Shells. Like beach sand, seashells can carry dried up salt from the seawater. If the shells are otherwise clean smelling, just rinse them in a bucket of water for a day and let them dry afterwards. If they smell nasty, just toss them. You can soak them in bleach, but it's more trouble than it's worth... especially if there's a dried up creature inside!
Use Epiphytes: They tolerate indoor lighting and infrequent waterings with ease. I've used Tillandsias, an epiphytic cactus (Hatiora) and a stem of a milkweed relative called Dischidia. You can buy Tillandsias at www.airplant.com, Dischidias at www.epiphytica.com and Hatiora (and many other epiphytes) from www.tropiflora.com. Succulents are tricky since they tend to bake inside their dish if they get the full sun they prefer, but they also work well.
Avoid Tapwater. City water is often 'hard' or filled with salt and mineral deposits that will end up making your terrarium a crusty mess. Like many of you, I'll still end up using tapwater out of necessity, but use rainwater or filtered water whenever you can.
Make it Your Own. Use your favorite beach finds (I've used sea glass) or make your terrarium in an entirely different theme! Try a desert theme, forest theme, or even create a miniature garden The sky's the limit!
Still have questions? Feel free to ask away by email or by leaving a comment below!