In my personal experience, the magnetic scrapers don’t work as good as they might say. The ones that’s look like a sponge on a stick are a bit difficult because you can’t really see all the diatoms when looking down from above and that leads to scraping too much of the wall in one spot that ma possibly disturb the substrate and cause waste to be free floating. I use a magnetic scraper and sometimes the stick one but prefer the magnetic because you can see better where you’re scraping and if there’s and algae in that spot but the downside is that it takes a bit longer to remove the algae from that spot. They both are good choices but both have their pros and cons like any other product. In my 40g I also have a UV sterilization light that works absolute wonders.I am interested in reducing nitrates in a 30 gallons if you know a product that works please let me know.
Oh sorry i misread the title. I apologize for the misunderstandingAlgae scrubber and scraper are two different things.