i was recently in one of my LFS 's and noticed that a lot of their display tanks were full of plastic noodles can anyone tell me if this is a form of their filtration as i was under inpresssion they used sumps most of the time and huge sand filters

thanks

james

Could be something for the fish to play with perhaps? Don't think it would get enough oxygen at the bottom of the tank for the bacteria to survive? Might be wrong though.