I found Verticella on the glass of my Aquarium.

Step1 – Find yourself an Aquarium and a glass slide and scrap the Aquarium glass with an angle of about 20° degrees between the glass of the aquarium and the glass slide, scrap until you see stuff like in the above image.

Step2 – place the scraped stuff on a new glass slide with some water and cover it with a cover slide.

Step3 – observe the slide under a Foldscope. Now if your aquarium has any culture built-in, you will find something, you don’t find anything then you just have to wait for some days to if the culture will build.