if you do decide to use gravel, the recommended size is larger than sand, but
smaller than the flourescent painted gravel in most stores. I believe the size
range is 2-3mm, but I could be mistaken.


My 10 gallon tank is filled with plants living in blue WalMart rock of
the course variety.

The tank had a standard 13 watt florescent and no CO2 for the longest
time.

So it's not impossible. The plants just don't grow as fast. Some
think that's a good property.

Of course "if you are building your substrate today, do it right. The
substrate is the hardest thing to have to replace."