The bulbs we use come at different spectrums to provide the growth needed. Corals use specific spectrums, which is why you'll see bulbs in the 10k-20k range. Algae will increase growth when these bulbs age, as the color spectrum changes with time. I'm not sure what freshwater uses anymore in terms of spectrum.
What kind of T5 unit are you using? Did you get your bulbs from Petco?
Your lights are not enough to sustain life for a nem... The reason he said ur lights sound like a freshwater set up is because they are not high output and the brand. U would need at least a 6-8 t5 HO bulb set to sustain a nem.