My light has 4-54watt T5s, I'm using a DIY CO2, and just started the EI this week. I was using Flourish twice a week. I have 3" of flourite under the sand. My tank is a 55 gal long
Follow the EI method and you should see amazing growth. I have a 50g tank with a similar light setup, I had to cut back to 2 bulbs because the plants were growing too fast.