Best way to clean algae at bottom of tank & curved corners

[Mike H2020]

What’s the most effective way to get that layer of algae that’s right where the top of the sand is on the tank bottom without Scratching the glass with the sand and also it is a bio cube 32 with the curve corners what’s the best way to get the stubborn Algae out of the curved corners of the glass. Thanks for your suggestions

 

[Bo.]

I use a toothbrush