I made a under sand filtered fish tank yesterday. It's like an under gravel filter but using a fine mesh and sand instead of gravel. The purpose being to filter better, and provide way more surface area then gravel.
People on the internet say it's impossible because the sand will clog too quick but no one who commented seems to have actually tried it so I figure I'd give it a go.
I just used a $20 Kmart special as a proof of concept. So far, so good!
Like so many opinions on the internet it seems like the people who post and the people who actually do stuff are two seperate circles on a Venn diagram.