So I accidentally bought the wrong size of these filters. Apparently I have a 40 gallon tank for 2 turtles and these filters I recently bought are not big enough for the system I currently have. I'm very positive that it will do a better job for smaller tanks under 20 gallons.
I bought my 1st pack of these to add to my canister filter and I think they work well. My canister filter has a bunch of different little compartments that had sponges in them, so I took one of the sponges out and replaced it with these dual carbon pads, and I believe it has helped the water clarity and quality overall.
Bought because they said helped with odor didn't make a difference.