You can read the article on plenum by Bob Goemans.
http://www.saltcorner.com/Articles/Showarticle.php?articleID=23&i=1
I setup my plenum in 2004 and its still in my tank today...after 18 yrs. Do note that plenum system is meant to tackle the nitrate issue only. However, there are still other major issues like phosphate, hardness, etc that we still need to tackle.
I also diy and setup an algae turf system in 2005/6 and it is my main filtration ever since. I even retired my skimmer shortly in 2007. Algae turf can tackle both nitrate, phosphate and other nutrient issues as algae is so efficient and dynamic. Just my thoughts and sharing my experience.
Cheers