Lets see if I can describe this...

[G1GY]

Originally Posted by Fish

Anyone else able to comment on whether or not the water would be slowed too much by a fine sand?

Thanks,
- Chad

The water would be slowed going through the sand unless it was suspended like it is in a fluidized sand filter.

Also, how do you keep it from falling through the under gravel filter grate?

If you did find a fine enough grate, the water pulling down through the sand combined with detrites would turn your sand bed into concrete in no time.