Never Clog Air Stone
These are the best air stones out there. They are weighted so they naturally sink. They can be taken apart so that if they were to ever clog, they can be cleaned. At 10+ years of using these I've still never had one clog. They are very low back pressure which doesn't wear out your air pump and they work great inside sponge filters. Really they are the best air stone money can buy. Instead of replacing the cheap glass/ceramic ones every 4-6 months as they get worse and worse for bubbles, install one of these once and never worry about it again.