Yes, I saw the link, and IMO that's really light substrate. I don't think it's the source of your issues, though, since you've got ich in the tank. Just because you can't see all the parasites on them doesn't mean the fish aren't feeling them. Most sick fish hide. I think once the fish are better and the plants have filled in more they're more likely to be out and about.
You don't have any dither fish, though.
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