Some peoples troubles are others dreams...
I would love mine to be as low as 5ppm.
In my 75 it's fully stocked, 3 eheims, and even with weekly water changes I work hard to keep it near 20ppm.
In fact I added a slew of plants in order to help bring it down from where it used to hover, around 40ppm.
In my 210, it's considerably under-stocked, large sump, planted moderately, weekly water changes, and I'm still near the 10ppm range.
I have yet to actually make use of those 3 pounds of KNO3 that I bought and thought I needed for the plants, grin.
Wow. And I was worried all to heck because my cycled tank is staying around 20. I figured it had to be 0, but I guess that is impossible. I will be moving some of the fish to a bigger tank once it is cycled, so maybe that will help it.