If I recall correctly a *guideline* for hydro is:

first 2 weeks, no nutrients
third week (or first set of true leaves) - 1/4 strength
fourth week - half strength
fifth week - full strength


These are five weeks old already, ppm around 300 (it raises) which is only 100ppm higher than the highest rated tap water i've seen. (Im using reverse osmosis water with ppm of 25)



Here are two shots from 14 days ago