I'm out for the week, so I can't follow up this issue for now. I'm eager to know what will be up once I return
@AnIsleAteHer Household H2O2 (3% IIRC) can be used as a spray by diluting 1/2 teaspoon into 1cup of RO water, like I've used. As far as I know though, it works best as a preventive fungicide and is of not much use for algae, probably even less once it's already present in the media. I personally would repot those seeds into milled LFS like I have used here. In my case, if it truly is algae, it's the first it happened on LFS, whereas on mixes incorporating peat and/or perlite, algae have been an issue at times. Try cleaning the affected seeds with a small paintbrush to remove algae but I would mainly focus on those that aren't affected so far. Be sure the seeds touches the moist sphag. Just my 2 cents!