on of the most popular
sintered glass products on the market.
Pot scrubbies are amazingly effective in the sense that they have (give or take) 370 cu/ft per pound and are incredibly cheap, sintered glass (mainly the brand mentioned has about 18,700 cu/ft per pound.
The reason everyone USED to love pot scrubbies is because to fill a 75g sump with sintered glass would be ridiculous. Everyone loves it now... well I don't think they know why, just that everyone else does so they should too. My point is, you aren't filling up that much space, so a couple of pot scrubbies won't be near as efficient as some good quality media. Sure it may be more expensive, but in the big picture... it's still not that expensive.