And just because you have a lot of plants doesnt nessicarily mean that they are the main bio-filter. Remember that some plants grow slow and therefor dont take up as much nutrients as fast as other plants. So you need your plants to grow fast, to get really fast growing tanks your gonna need to do a little extra work, high light, high CO2 levels made artificial from pressurized kits, and some sort of doing technique, EI would be the best for this. This doesnt nessicarily come cheap....
But you can also get fast growing plants in low light, but that would mean that your plants may not be the main bio-filter.