I have a ten gallon tank and a Tetra Whisper HOB filter that is rated for tanks between 10 and 30 gallons. It gets everything clean, but in my smaller tank it turned the majority of my water into a strong current and was bothering my snails and frogs. I tried the water bottle trick I'd seen online, but it just seemed to redirect the current. Figured this out this morning and love it...I hope it helps someone else out there, too! (Sorry for the 'dirty' white filter pad...rinsed off my filter cartridge after adding it and got the new pad kinda gunky. Whoops... :;nin2 You just need four thin zip ties, a sheet of aquarium filter pad, and some scissors. Cut a square or rectangle out of your filter pad so it completely covers your water outflow plus a little more, then hold it up to your filter and see where you want to hang your zip ties. I poked my scissors into the foam to make little holes in it, then threaded it through my zip ties. Since there isn't too much actual pressure on the sheet of white foam, I was able to safely zip tie it to the plastic bio-foam holder that comes with this style of filter to keep it secure. This isn't adding any strain to my filter and I'm still getting plenty of water movement at the surface, too. The pad stays right at the water line, and I haven't caught anyone trying to eat or poke at it. Everyone in my tank seems much happier now!