Full Blackout Help!

Hi all! I'm having a slight algae problem in my 18 gal tank, but nothing like a full bloom. Mostly small hair algae on decorative bits and on the side of tank. When I posted here before, someone suggested a full blackout. Would a 48-72 hour blackout be harmful to swordtails, neon tetras, guppies, and snails?

Photos for reference

If you only have plastic plants, then I would just scrub it off. I find it to be easier than trying to eradicate it. Guppies also like to eat algae, so I would potentially leave some behind on the back or side walls for them to eat.

If you do go the blackout route, I don’t believe it would harm the fish. I’ve left my fish when on long vacations with the lights off all the time, and I haven’t seen any signs of stress.