These aerator stones are well constructed, but be advised that each stone contains a pressure-relief plug. My carbon vane compression aerator system has two pressure relief valves built into the manifold, so I don't need or want pressure relief in the stones themselves. Over the past 22 years of operating a pond aeration system, I have used at least a dozen stones with pressure-relief plugs. The failure rate of those plugs is virtually 100% once the stones develop a small layer of organic matter. I decided to keep and use the Pro-Glass stones, but before using them, I removed the plug and epoxied the hole. The slightly modified stones work very well.
