Our dual pane windows have all fogged up and had to be replaced. The salt air attacked the aluminum frames and within 3 or 4 years penetrated between the panes. Santana Glass replaced the glass with a single 1/4" piece if glass. The dual pane was originally 1/2" thick, ( 2 - 1/8" panes of glass with a 1/4" aluminum spacer) They added a 1/4" solid aluminum spacer to bring the thickness back to 1/2" and enable the original locking strips to still be used. The modification turned out very well, looks like it was originally made that way, and doesn't leak a drop. We were very happy with their work. No more streaked or fogged up windows to spoil the beautiful view!