SegartyAquarium Bio Balls, 1 inch Koi Pond Filter Media Bio Ball with Sponge for Aquarium Filter Canister Filter Biological Filtration for Freshwater Marine Fish Tank Sump (100 PCS with Mesh Bag)

Works great!

Using with biologic filter media. Love the zipper instead of the string, not sure about durability yet, though seems well made for what it is and the price point

I did see a different on water it more clean and clear

Other than the narrow top, where the zipper is, these are exactly as advertised.

I have it in my waterfall to help keep it clean

Water clearing up already!

It’s all good.

These are great bags for my HOB filter.Rather than buying new things every month from the manufacturer, I tend to use whatever I want in my HOB filter. I’ll use an ammonia pad if I need it, phosphorus beads, whatever. And these bags come in very handy if I need something held in place. I use one for my bio rings permanently and have another one that i’m using temporarily for my phosphorus beads. If I need to seed some more bio rings for another tank, I can use these for that option as well. These bags are super handy to have around, no doubt about it. I recommend.

As described

The zipper is a nice feature instead of a drawstring, but I didn't read the fine print where it said not for fine particles. I found that my purigen easily escaped through the holes in the mesh bag. Not a total loss though; we'll find other uses for this handy bag.

It's difficult to find the right size an these fit perfectly. Great!