Your magnet isn’t strong enough, or maybe there’s a problem with the surface of the scraper bit. Different thickness of glass requires different strength of magnets.

Mine is too strong, I wrap the handle in cloth to increase the distance.

My scraper takes algae very easily, but mineral deposits seems to require a blade.

I guarantee there are magnets that will create enough force to remove algae, they might just not come stock on these cleaners

Nah mines strong AF. I have trouble splitting it open. Cleans great ✨