I don't think a blackout would help much. I'd be inclined to remove as much by hand (an old toothbrush is pretty good for this) as possible & resume glutaraldehyde treatment, but at a 1mL/gallon. It will take longer, but your moss should be able to handle that, at least longer than the algae...
If the clado is pretty localized, you could dose some of the excel by pouring it onto a piece of filter floss or a little bit of spongy material and rubbing down the offending areas, or just lodge it in the area so the Excel will be a little more concentrated there (for a whiel, anyway).
If the clado is pretty localized, you could dose some of the excel by pouring it onto a piece of filter floss or a little bit of spongy material and rubbing down the offending areas, or just lodge it in the area so the Excel will be a little more concentrated there (for a whiel, anyway).
