Fertilizing Based on Presence/Absence of Pearling....

I just hooked up a DIY CO2 bottle to the intake of my AC filter and of course my tank now looks like a champagne glass, but it got me thinking. I wonder if I could avoid testing anything and only add fertilizer when the obvious accelerated photosynthesis stops. I realize that the inputs are light, water and CO2, but presumably it would slow down in the absence of nutrients since the plants would not be able to properly grow and maintain themselves without nitrogen in the chlorophyll molecules etc.

Thoughts?

I have a 10 gallon tank with 3 f17t8/865 bulbs for a total of 5.4 watts/gallon. Everything is growing great and pearling like mad.

It's all planted, but it is not yet heavily planted. It will be soon though as a result of growth.

As far as fish go, I have 12 of these: http://www.petfish.net/articles/Barbs_Tetras_And_Minnows/Boraras_maculatus.phphttp://www.aquahobby.com/gallery/e_Boraras_maculatus.php
as well as 5 amanos and I just added 30 red cherries. I also have 5-6 species of snail.
I don't plan on adding any other fish, though the shrimp will probably reproduce.