I am anything but an expert here (sometimes I literally know nothing!), and though different manufacturers produce different 6500K bulbs, I would be surprised if your 4 tube fixture produces anything close to 30,000 Lumens. A typical "Gro-light", 6500 K, 4' T5 tube would produce around 90 lumens per watt. You'll have to check your tube wattage, but again, an average would be something around 54W.
Not that this is terribly important. That's still a great fixture to use. This fixture will certainly produce enough light to aid your plants.
