How strong is the Tetra Whisper 3i filter?

I have had that filter before. It came with the tank I purchased. Yes it is for up to 3 gallons. But, the filter does not work well at all! It says all you need is the filter and no bubbler because the filter runs through a bubbler. And that is supposedly adds oxygen to tanks just like a bubbler along with filtering, wrong. The filter hardly cleans as well. I used the filter without a bubbler thinking it would work and the fish died lacking a bubbler. Try any other filters besides this one!