help me save this tank

[Dtuck724]

This tank is filled with red slime and hasnt been kept up with, a small clownfish has been living in it for years though. I just need a few tips to save this tank.
https://www.dropbox.com/s/e488n2zrz07ak1r/Photo%20May%2019%2C%204%2009%2003%20PM.jpg?dl=0
https://www.dropbox.com/s/ich701he08e6dwb/Photo%20May%2019%2C%204%2008%2052%20PM.jpg?dl=0
https://www.dropbox.com/s/l4v2s3cc1qoo4pr/Photo%20May%2019%2C%204%2008%2044%20PM.jpg?dl=0

[Chevrefils]

Yikes! Is this yours? If it were me I'd take the rocks out and put them in a dark tote for a few weeks to kill all that cyano. I'd then start on doing some water changes, clean the glass and get some clean up crew. You could also just leave the rock in and keep the lights off for several days. Do you have a skimmer? You need more nutrient export.

[jon99]

Yeah, major nutrient overload and neglect. Don't do anything in haste.

Start by scraping and siphoning as much algae as you can, but keep the water changes to 30% system water volume or less. Get a gravel vac and hit the sand, but again not all at once. Do 1/3 of the gravel every couple weeks. I bet it's full of detritus. I wouldn't add any livestock (including cuc) for now. What kind of filtration is being used? It may need upgrading.
Some will recommend removing and "cooking" the live rock to remove nutrients. I dont know much about this. Never cooked anything I didn't eat.

[Dkuhlmann]

I don't like it but I'd use Chemiclean on it, but follow the directions to the T