6.5gal plastic big mouth bubbler question?

Hello I am wondering what kind of Sponge one can used on the inside of there 6.5gal plastic big mouth bubbler without scratching the inside of there plastic fermenter ?

I do rinse with the water hose untill all the gunk is out. Than fill with water. And use a soft cloth. To clean and avoid scratches. On brew day clean with. Starsan. Thats it

Here’s a previous thread along the same lines. Cheers!