Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I have used all those, and find the single edged razors work best, but you have to be VERY careful with them, especially on curved tanks. Not for acrylic at all.
The Mr Clean things work OK for softer stuff.
Just today I was cleaning a used tank I got over the weekend. Empty, of course, it took CLR (The strong chemical that removes Calcium, Lime, and Rust) and razor to clean it.