So...... Napa "Floor Dry"/Diatomite #8822 fully screened and washed ftw ?.......or......
Turface and rice hulls......Now we`re getting somewhere......
Later......
i've been using unscreened but heavily washed turface with rice hulls at 3/1 turface/ricehulls successfully up to now but with the saturation pulsing and the larger medium volume i'm pretty sure i'm going to screen mine and omit the rice hulls next time.
now i see ichabod has said the 8822 needs screening too.
you want a non-compactable medium with at least 30% air porosity that doesn't float.