Hello, Let's start by saying I'm new to canister filters. I've been taking care of a 65-gal aquarium successfully for 6 years now. I'm not an expert by any means. I've lost fish along the way (mostly during vacation) although two have persevered; a Khuli Loach and a Cory Catfish. I have an aquaclear 70 and its impaler has been worn out to the point that it will not spin. Luckily I had a spare aquaclear 20~ish and because it's motor fit on the 70, I switched it out, however, I have a 20gal~ish imapler on a aquaclear 70 because the six fin fan of the 70, doesn't fit the impaler on the 20-gal. It just comes loose. Because getting either a replacement impaler/motor or a whole new aquaclear is so much and I've always wanted a canister filter and I found a suitable canister filter that was not expensive and I've wanted to move the HOB to the other side of the tank but I would need to sand down the wood trim because the wood trim + the glass is 1-inch thick, I ordered a Cascade Elite 1000 canister filter for $110. After a lot of research I decided to spend even more money (of course) and ordered some BioHome Ultimate for the top two trays and the typical course, medium and fine foam on the bottom tray. Now I've come across a few suggestions that put Fluval pre-filter media below the first tray. There seems to be enough space for a single layer as long as they are laid down flat. Now I can understand if this can help disperse the water flow so that the water filters through the media evenly vs. tending to flow mostly through one spot and it also collects large debris as well, but is it worth it? Is dispersing the flow evenly even an issue especially when the gap appears to be 1/2-3/4 inch?