I recognize this is possible in reef systems but I'm not aware of a biological filter that can remove nitrates in a freshwater system. Anerobic bacteria that consume nitrates are not nearly as efficient as aerobic bacteria that consume ammonia and nitrite. The issue is usually a matter of transporting nitrate to anerobic bacteria without transporting dissolved oxygen as well.
I'm not saying it's impossible, just that I'm not aware of it being done in a freshwater system. I'd like to see some refrences that describe this balanced biological filter you suggest. Based on my understanding of water treatment in home aqariums it seems complicated and expensive to acheive a balanced system without water changes or plants to remove nitrates.
To keep on track, I've had a planted tank setup for about 6 months before rescaping, I've only had planted tanks for about a year now, one of my tanks I plan on leaving as is for a very long time. In the past I've had non planted tanks set up for as long as 2 years without re-scaping.
Go check out some of the amazing Natural Planted Tanks on Diana Walstad's El Natural forum over on APC- they will blow your mind!
This was my low tech RCS colony. I had it set up for 4 years, and only took it down b/c I moved the E. tenellus into my 90gal and needed the spot to set up my 29gal.
Really the only change I made during that 4 year period was I ended up pulling Cabomba b/c it kept getting too big and would get pulled into my filter intake. Oh yea, plus I removed java moss b/c it kept taking over too. I had to boil my driftwood to finally kill the stuff so it wouldn't keep growing back.
That's when I put the Pellia and Flame moss in, instead. Only changes in 4 years... LOL
I was going to plant the Repens you see floating in the pic to have a background plant, but my cat got to it first while I had it in a bucket sitting beside the tank and ate it. (We can't keep any houseplants b/c of him, Grrrrrrrr)
I like setting up tanks that are low maintenance and last a longgggg time. Once I find something that works, I stick with it.