For those of us with acrylic tanks

[NedFlounders]

I found the PERFECT scraper! I've used a bunch of different methods for getting the harder coralline off the acrylic, but this has been the most successful (better than a credit card):

https://www.pamperedchef.com/shop/Cleaning/Cleaning+Tools/Pan+Scraper+Set/2610

 

[tzylak]

Hey!! Wait a minute!!
I got something like this in my kitchen junk drawer!! Picture a bright light bulb over my head!!!
Thanks!!!