Yup, get your flouro close to the plants. Tall and skinny means stretching for light. Did you know also that HPS light, that appears very pink, actually signals the plant to stretch much more than MH light, whcih is more blue? So a lot of growers veg young plants under flourescents of the 'daylight' or 'cool white' type, and save the HPS for flower. IT's not BAD to veg under HPS, but adding blue light will help keep the plants short. What style flourescents are you using?