Calling Acrylic tank gurus -- What do you use to clean the inside acrylic?

Ok, so I don't have much experience at all with acrylics, all I know is they are soft as all get-up. I'm wondering what others use to clean the inside of their tank 'glass'. I've seen the felt mag float cleaners and they seem to be pretty good. My issue is that I have sand, and if I'm cleaning close to the bottom I'll pick up some sand and scratch away without even noticing it. I've already put a few scratches in the bottom side of my tank from picking up sand frags on my cheesecloth without noticing. ergh!! ><
The obvious thing would be to keep your tank parameters so that you rarely have to clean the inside, but in my case, I've just added floramax, and there is dusty mucky goodness on the tank walls that I have cleaned off, resulting in a couple minor scratches at the bottom.

Comments?

 

Pretty sure many people use credit cards to scrape the glass.

 

The people at underwater world use acrylic squares to clean the acrylic tanks, maybe that will help?

 

I've always used paper towels. Works like a charm.

 

My husband's first tank was acrylic. He could purchase specific algae scrubbers that were safe for that product.

 

And none of you have had any issues with picking up sand in the media when you are wiping resulting in scratching?