I'm using this filter in a 35 gallon show-tank with a fairly large turtle, and it is hands down the best over-the-side style filter that I have come across. My old filter Tetra Whisper EX45 Filtration System wasn't cutting it so I replaced it with this one.
WHAT A DIFFERENCE!
For starters, the Marineland filter is much larger and the filters cartridges are much larger as well. The uptake tube is roughly twice as large and comes with an extension that allows it to draw water from near the bottom of my tank, where all the gunk is at. The previous Tetra filter could only get about half-way down.
The next improvement is the addition of a media tray which lets me put in more activated carbon or zeolite, or whatever depending on my needs. From my experience, this means that I don't need to change filters as frequently and I can have custom filtration right out of the box. With the Tetra filter, you can put in a biobag Whisper Bio-Bag Cartridge - Large - 12 pk. - Unassembled but I find the Marineland system more robust.
From more quantitative testing, I've found that the ammonia levels have stayed consistently low with this filter. With my old filter, ammonia levels were all over the place and it felt like I was declaring chemical war.
This unit is also pretty quiet and it hasn't had an impeller problems. I do find though, that you really need to prime it (fill it with water) before turning it on, otherwise you'll hear grinding sounds and it will take a long time for the water to start flowing, if at all.
At the price point, I don't think there's a better widely available filter than this.
