Seriously Sam if you have much more than 2wpg/ or more than ~18W on 27L you will soon descend into an algal abyss. lol. IME there is no faster way than with too much MH light over a tank to incite the algal infestation.
But I do wish you luck.
One nano planted, if you use the right sized plants, is a grand sight.
Your biggest problem is maintaining a balance of everything in such a small environment.