Planted Tank Guru
Join Date: Nov 2009
Location: Missouri united states
Smaller grain material like sand and soil, will end up underneath plate for under gravel filter.
Were it me,,I would either use all fine gravel,or go without the undergravel filter.
Goldfish would welcome the hard water that coral sand produces, But Angelfish and tetra's prefer softer to neutral hardness pH.
30 gal is in my view a bit small for Angelfish except when juvenile and also small for goldfisn depending on type.Some get quite large.