A bad power factor means that there is an inductive (lagging) or capacitive (leading) current flow that does no work but still loads the wiring.
A big fluorescent light installation may for example draw 15A without correction but maybe only 9A with correction.
If you got a worse power factor with a capacitor installed then the question is what kind of ballast do you have in that T5 lamp, iron-cored inductor or electronic?
You probably have an electronic ballast, which is inherently capacitive already. The solution is then not to add more capacitance, but maybe/ rather an inductor.
Oh, and don't use pf behind the number, it may be (mis)interpreted as pF (pico Farads). The power factor number is actually unit-less.