My all time favorite sponge filter, the real name “Xinyou” is avoided. I've tried them all and I gravitate towards this fine-mesh sponge. Sponge filters are the hands off solution that is par to none. While the fine sponge filter may clog quicker than a coarse sponge filter, the benefits outweigh the cost. Water is kept clearer, baby shrimp do not get caught and trapped in the sponge so when you squeeze clean there’s no casualties. Fry and shrimp can eat from the sponge as a backup food source, if the air stops working the bacteria colony stays intact. I use a black background with a black airline which hides the sponge filter but a little Aqua scape planning can also obscure a sponge if that concerns you. The smallest filter here I like for 10 gallons but they always rate them much higher and you can go much lower, the "preferred" is what I like to use them for. I took a photo of a 10 gallon Imagitarium tank for scale. Clean sponge filters with a squeeze, push water through the airline with a 500ml water syringe if it clogs, this sponge filter will run forever if you do those two things. The point of failure is usually the airline going brittle after a couple years use. Place air pump above tank waterline and you won’t have to worry about check valves. Will ship everyday USPS if it’s dry supplies, anything wet and alive ships Wednesday, dry goods will ship with wet on Wed if both are ordered. Model no: Small: xj-2810 Medium Tall: xj-2811 Medium Wide: xj-2812 Large: xj-2813