VIVOSUN Air Stone 2PCS 4 X 2 Inch Large Air Stone Cylinder for Aquarium and Hydroponics Air Pump (2PCS 4 x 2 Inch)

Works great

3 of the 4 I bought worked beautifully; the fourth, I had to reseal - the air blew right out at the connection, instead of through the stone. Overall, these air stones are large, but not as effective as others I've had. I bought them to use in Koi pond moving bed bio-filters, and they will suit that purpose well.

There are a nice size and fuel heavy and well-made. But one thing I have to say is that the air bubbles are not coming from the whole stone. Only some the area close to where the air tube comes. Maybe he hasn’t been long enough and the air will start coming from in a few days. But it has yet it hasn’t.

Expected a little more from these considering the size (I bought the combo recommended pump and everything ) No huge deal as I have one of these in the bottom of my hydroponic setup and a smaller more bubbly stone suspended closer to the root zone of plants.

These are tough airstones. I am amazed that they still work at all after the beating they took in shipping. Bashed so hard, they were knocked free of the factory cardboard packaging. Some chips were knocked loose. Amazon put these heavy, brittle stones in an oversized, non-padded plain manila envelope. That's no way to treat airstones. Isn't Amazon supposed to be in the shipping business? Fail.