[TowerTalk] Cleaning mildew off tower concrete

[EUGENE SMAR]

TT:

     As part of my Trylon tower maintenance this year I want to scrub the
concrete base to remove the green mildew, or whatever it is, that has
accumulated on the surface of the concrete.  FYI, the tower is in the middle
of a group of trees in my back yard and the concrete base is in the shade
for most of the day.  The mildrew is growing in an area immediately below
the tower steel.  That is, it doesn't appear near the edge of the concrete
base nor on the concrete in the center of the tower.  I'm guessing it's
carried off the tower in some kind of runoff.

     My initial thought was to scrub the mildew with a mild solution of
household bleach, maybe diluted 1:1 with water.  My main concern, however,
is for the tower material itself.  It's not galvanized, but, as Trylon call
it, a passivated G-90 coat pregalvanized sheet steel material.  I don't want
to damage the G-90 (?) coating with the chlorine bleach.

     Does anyone have any advice on how to clean the mildew while still
protecting the steel of my tower?  Many thanks.

73 de
Gene Smar  AD3F
P.S.  The mildew looks bad from the back deck, only thirty feet away.  If it
were out of sight (on the lower forty) I wouldn't care as much.