Scrapping Glass without scratching

I use the whole kent line... they come in several different handle lengths. There's no way to be careful with the 36" one (or something like that). I'm just holding on the very end where there's this foamy stuff. When I get close to the bottom, I scrap down, then lift up, scrap down, and lift it. I really don't watch what I'm doing because I have my eyes on what my fish are doing. One slip and I get hit.

 

i have a acrylic tank and the credit card works great on it. the credit card works great for along the sand line also. since it glides by the sand

i also use a mag float but i i put a piece of felt on each side of it.(zeroedge tank so i have 2 sides to clean) i feel even the mag floats made for acrylic are to ruff on the acrylic. so thats why i lay a piece of felt on it. i also change the felt with each use. so if by chance i picked up sand it will get washed away when they go into the washer with the sump socks.
acually the felt is two of the acrylic cleaning gloves cut up.