Who Gives A Fish Forums

Some folks might not agree with adding fish to tackle algae issues, but I've found that with ottos or a small pleco, you'll rarely need to scrub the glass, they take care of it for you.

The flicking is likely due to water quality issues or irritants, possibly parasites, but in your case it's probably just the elevated ammonia and nitrite levels that need to be sorted ASAP. I've never seen my pleco, who's also in a sand tank, exhibit this behaviour.

Edit: I've had issues with ...

"Black out will not kill BBA" is a common misconception. The blackout method is actually used to starve the BBA, as it relies on light for photosynthesis. By depriving it of light, you're essentially starving it.

I'm no expert, never kept this type of fish, but what's up with the one zooming around the glass in the corner?