| It means that once lava rock clogs, there isn't really much you can do except replace it. Even when used in showers, the slough-off from the bacterial colonization will eventually clog it. Usually takes 2-3 years for it to happen.
The pumice or cinder stone allows SOME water to pass through it but not equal to what flows around it. And, yes it is only temporary, until it too clogs up - it's also like working with razor blades so make sure you wear gloves when handling it. |