Gina1960 said:There isn;t anything you can do about the spots.The white portions of the leaves tend to do it no matter what on leaves where these are large patches of white as opposed to striping interspersed with green and speckling. There is no chlorophyll in the white and in a large patch there is no green to help that part of the tissue stay alive. Its like if you put a tourniquet on your arm too tight and the blood flow stopped and it got gangrene.
The light looks good, an albo-variebata like yours that has a high degree of variegations needs very high light for the green to make up for all the white. Using filtered water will have no effect on the spots. Just don;t over fertilize as that may contribute to fertilizer burn
Gina1960 said:If that is your best window, then yes it looks fine.