After the sub-base has hardened, take the landscaping rake or the
backside of a regular rake and gently remove stones sticking above the
surface of the sub-base. Sweep the loose stones off of the
sub-base. You will find areas where the sub-base has pits, etc.
from the stones being removed. Add small amounts of 30-35 grit
sand and lightly spread it in those areas before laying the golf
putting green on the sub-base.
The sand will fill in the holes and make the bottom of
the artificial putting green smooth. The sand also allows the
putting green to freely expand and contract with weather
conditions.
