For decorations this tank uses only shells and sand as substrate. In this photo the tank is set up with play sand that is very fine grained.

Substrate

I started the tank with play sand, because it was most conveniently accessible from a hardware store. Play sand is very fine, which unfortunately means it tends to clump together. Clumping can lead to anaerobic pockets in the substrate, which can produce chemicals that are harmful to fish and have a bad odor. This problem can be avoided by using pool filter sand, and I swapped the tank over as soon as I worked this out. Pool filter sand is not more expensive than play sand, but a little coarser. Apart from the avoided clumping issue, it has the advantage of usually being a lot cleaner out of the bag. I didn't have to was mine at all, while play sand can be a pest to clean. Pool filter sand is available for wherever you can buy pool supplies. In my area that's the Litehouse Store Chain. In those States of the US that suffer a cold winter during which outdoor pools can not be used, pool filter sand can be hard to come by during that season.

Apart from the cute little fry, this photo shows the coarser grain of pool filter sand as compared to the play sand used in the image at the top of this page.

Shells

I am using escargot shells from the Gourmet Food Store. They are very attractive looking, and a good size for most shelldweller, and light enough that the fish can carry them around and decorate the tank to their liking. While the brevis in my 240G setup tend to hide all shells they are not using by digging them into the substrate, the occies seem to think the more shells the better. Accordingly, I tend to have plenty in this tank.

One small drawback with escargot shells is that they loose their attractive look after 12-18 months, they become stark white, and they become thin and brittle. Apparently my water is softer than that of Lake Tanganyika, because there the shells are reputed to last for decades if not centuries on the lake floor, while mine dissolve in a comparatively short time. Replacing the shells is no big deal, but nevertheless I have been thinking about trying another type, possibly a thicker and slightly larger marine shell. This would also be good since especially the brevis have become larger over the years, and the male doesn't stand a chance of squeezing into an escargot shell any more. A source with good pricing seems to be Shell Horizons - only which ones to choose with that huge a selection!

A bag of escargot shells from the Gourmet Food Store.