The only time I would spray is if you really need to.... like to knock down powdery mildew or Spidermites....then only apply your spray prior to putting the plant in the lights and let it dry for 15-20 mins .... the moisture will usually evaporate during the light/heat exposure.

I'm having to spray out a couple of my plants on a weekly basis with water/h202 due to PM...if you stay on top of it this works