Wow - how cool to get so many replies!
The substrate is medium gravel (fruit salad I think) - came with the tank so not too sure.
Tank mates are: tetras - neons (15), black phantoms(5) & congos (3); guppies (8); corys (2) and gourami - pearl (2) and blue dwarf (2) and too many platys (can't stop them breeding - started with 2, gave away 25 and now have about 20!) all too pretty!