T5 grow lights aren’t the only fluorescent lights on the market, because there are T4, T5, T8 and even T12 lights that all compete with each other which is why these comparison posts are so popular and sought after. This one as you can tell by the tittle is one about comparing T5 fluorescent grow lights to T12 ones and figuring out which is better in the end.
First a little background on fluorescent lights. The letter T in the name of the light means that the bulb has a tube shape, but the number next to the letter represents the diameter of the tube shaped bulb, measured in eights of an inch. Which means that the T5 bulbs are only 5 eights of an inch in diameter (15.9 mm) while T12 bulbs are 1 and a half inches in their diameter (38.1 mm). To some this might not be a big difference but if you look at it then the T5 bulbs are more than a half the size of T12 bulbs, which means that they are more compact and will defiantly take up less space.
From the size also comes the second difference – efficiency. The T12 bulbs are much older than T5 bulbs (T12’s were first produced in 1930s, while T5’s in 1950s) and therefore consume much more watts while giving out less lumens. So the efficiency factor alone is a reason to choose T5 bulbs over T12’s.
Another age related thing is their life span. T12 bulb will last you for a very short period of time where as T5 bulbs last up to 20,000 of burning hours. That means that with T12 bulbs you will have to replace them extremely often, which won’t be the case with T5 bulbs, they will last you for quite some time (even if you would burn them 24/7 they would last you almost 3 years).
And lastly T12 bulbs soon won’t be easy to find because for example in 2012 the U.S. decided to change the Department of Energy regulations in favor of stopping all T12 bulb production. And because of the fact that some of the biggest bulb manufacturers are based in the U.S., the T12 bulbs won’t be that easy to purchase because they aren’t even manufactured anymore. And I am sure that many countries will follow suit because T12 bulbs indeed are very inefficient and simply an outdated technology that need to be replaces. And why not replace them with T5 bulbs.