  Lattice QCD solvers encounter critical slowing down for fine lattice spacings
and small quark mass. Traditional matrix eigenvalue deflation is one approach
to mitigating this problem. However, to improve scaling we study the effects of
deflating on the coarse grid in a hierarchy of three grids for adaptive
mutigrid applications of the two dimensional Schwinger model. We compare
deflation at the fine and coarse levels with other non deflated methods. We
find the inclusion of a partial solve on the intermediate grid allows for a low
tolerance deflated solve on the coarse grid. We find very good scaling in
lattice size near critical mass when we deflate at the coarse level using the
GMRES-DR and GMRES-Proj algorithms.
