I filled up the 2nd chamber on my BC14 with live rock rubble and pieces, took out the floss and charcoal, cut a piece of filter floss to fit the tray above the live rock rubble that I take out and clean every couple of days, but the stuff is so cheap you can buy it and make sooo many out of one package, our next mod is to use a locline fitting so we can split the return in 2 directions, and possibly to change the pump for a bit larger....but there is SO many things you can mod on these tanks, ie scrape off the paint from the back, put a light at the back and turn the 2nd chamber into a fuge......there is another "nano" site that has soooo many threads on mods for thesse. It's pretty cool! Of course, we can't just buy and it and leave it alone...we all want to make it BETTER
