The tubes in the picture are 48 inch tubes and that should be the standard you are buying. They are 40 watt bulbs. That is what you want. The Lumen output (amount of visible light omitted) is 3150 Lumens for the bulbs in the picture. That is pretty high. The higher the better.
The tubes were only $2.59 each. Next to them, in the store, were 48 inch tubes in a box that said plant and aquarium bulbs. They were $10.49 per tube. The difference is that the tubes packaged pretty for plants had under 2000 Lumens. I don't understand why they are under 2000 but your plants want high Lumens not pretty packaging.
I also had my original bulbs for about 3 years (maybe more) before they burned out. Seems like that is about the time frame because 3 burned out this week.
|Vegetable Grow Closet Bulbs: Gary Pilarchik|