The difference between the pool filter and your fluval is that, your pool filter is designed for different media. In the picture of the filter I only see 2 chambers, the first one is the strainer so leaves don't clog up the motor and the second chamber is the mechanical filter, specifically a micron filter. The micron filter is designed to push water through it and then the clean water is sent up through the middle. On your fluval, the water is forced through the entire filter chamber, it goes down the side of the media baskets and then is forced up through the middle. You would have to make some basket system so you could have the same thing work in your pool filter. One other thing to think about as in regards to the pool size and your tank, the pool doesn't have a constant supply of waste being added to it and it also has the added benefit of having chlorine in the water that would help to kill bacteria and break down debris that gets in the pool. The filter will work, but I don't think it would be safe for fish in the long run.