I have a large stump in my tank and it is very easy to use. I simply washed it then placed it in the tank and sat back and watched it. Cleaning is fairly easy, my plecos take care of anything that grows on it. They aren't expensive if you're willing to go out and collect your own too.
I also filter my tank with a sump and would highly recommend one for the size tank you're planning.They are easy to clean and maintain if set up right, it can be as simple as changing and rinsing filter socks. I think you'll find with a little DIY they are far more cost effective than other filters for large tanks, if you can't afford a basic sump for a 180g tank you're not going to be able to afford canisters or HOBs to filter it...