I use Mag-Float cleaners. Just be careful going close to the sand, especially if you have iron rich substrates like fluorite. The magnet can pickup iron particles and scratch the glass if the inside magnet part gets away from the outside part while it's touching the substrate. It can also grab sand if you don't go carefully at the bottom. I have three that I bought at least 10 years ago for various tanks and only had to change the pads one time (last month). They last crazy long and clean very well.