Invert for first 30 seconds then one every 30 seconds. Really no grain at all.
Recipes & dev times using Film Ilford Pan F+ 50
Ilford Pan F+ 50 at 400 in Agfa Rodinal 1+50
38 minutes at 20°C/68.0°F
Ilford Pan F+ 50 in Agfa Rodinal 1+25
6 minutes at 20°C/68.0°F
Ilford Pan F+ 50 in Agfa Rodinal 1+50
11 minutes at 20°C/68.0°F
Ilford Pan F+ 50 in Agfa Rodinal 1+100
1 hour (Stand developed) at 20°C/68.0°F