I actually built an in-tank overflow out of acrylic and had like a hob filter pump water out of the overflow. The overflow was for my 2.5gal so it was only 1in x 1in x 7.5in. I only took an hour to make and i never had to worry about the film again. If you have a small nano this is the way to go since an extra powerhead near the top of the tank would be too much current for xenia in a nano.