There's a white handled magnet that floats - mine doesn't.
It's much easier to drag this across the glass to clean it than using a sponge at the end of a small pole, but both work.
The magnets are for Glass OR Acrylic - not both, so be sure to get the one that applies.. Don't drag the magnet through the substrate. You don't want to risk scratching the glass or acrylic. If you do get it in 'sand', take it out and rinse it good.
You can even drag the magnets around corners...