T5 vs. T8 Tube Lighting [Which is Better?]

Heather Clouse
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What Does The “T” Stand For?

The T in T5 and T8 stands for tube, and the following number shows the diameter of the tube.

T5 tubes can be used for plants, corals, or in a minimalist “FOWLR” (fish only with live rock) set up. T8 tubes are generally used in planted aquariums and can also be used in reef tanks.

The T5 tubes are perfect for smaller tanks with limited surface area for plants, or to supplement light requirements.

Comparing T5 Vs T8 Lighting

The main difference between T5 and T8 light tubes is the diameter and the length of the tubes. T5 light tubes are 5/8 inch (15 mm) in diameter while T8 is 1 inch (25 mm) in diameter. T5 tubes have a maximum length of 40 in (1 meter). However, some companies sell T5 bulbs that are much longer.

T8 tubes, on the other hand, have a length limit of 84 in (2.1 meters). Since T8 bulbs are bigger compared to T5 bulbs, most T8 bulbs are brighter than T5 bulbs.

Most gardeners and aquarium hobbyists use T8 tubes in their lighting fixtures. They reflect more light to the plants, decreasing the number of lights needed to cover the same area. T5 light tubes are better suited for shorter spaces, such as aquarium tanks, where space is limited.

Another important difference between T5 and T8 is the quality of tube manufacturing. T5 tubes are much thinner and more fragile than T8 tubes. Most aquarium enthusiasts prefer fixing T8 tubes in aquariums as they are more durable and withstand water pressure better.

Typical Uses of Each Type of Tube Diameter

Light is the most important factor for aquarium plants. While it is true that you can grow plants in low light conditions, the quality of the growth will not be as good as with optimal lighting.

With artificial lighting, you have two types of bulbs to choose from – T5 and T8. Each of these bulbs works well and will do the trick, but they each have their pros and cons.


You probably have seen these bulbs at pet stores. They make good general purpose lights because they work well for fish. They are also good for your plants, except they are only getting 18-20 watts of light per bulb.

The bad thing is that you may need a lot of these bulbs to fill your aquarium. It is not economical to use for other uses, such as plant propagation or coral reef tanks.


This is the more popular bulb you will see at the fish stores. This bulb is a little longer and provides 22-40 watts of lighting per bulb. This means that you can fill a 60" aquarium with one bulb.

T5 vs T8 Bulb – Which Has Higher Energy Efficiency?

If you are looking to make efficient use of energy, T8 bulbs are generally a better choice than T5 bulbs due to lower energy consumption.

T8 tubes are larger in stature than T5 tubes. This gives them room for more energy-efficient components. Additionally, they’re often a little longer than T5 bulbs, which allows for better coverage even at greater depths.

The T8 tubes are widely used in offices because of their high-lumens capabilities as well as the color consistency they provide over the years. Another popular application of T8 tubes is vertical gardens where they’re used for superior coverage of an area.

Truth is that the T5 tubes draw twice the amount of electricity that is needed. This means that they leave the bulbs running on unnecessarily high heat for longer periods.

Frequently Asked Questions

Are T5 and T8 bulbs interchangeable?

When it comes to aquarium or terrarium lighting, T5s and T8s are two of the most widely used fluorescent bulbs. People often ask whether they can use T5 bulbs in their T8 fixtures and vice versa. My answer is an absolute “No”!

While T5 and T8 bulbs have the same electrical characteristics and fit a similar light fixture, they are not 100% interchangeable. The T5 is slightly shorter and significantly smaller in diameter, so the two tubes will not fit into each other's fixture.

Also, any slight difference in the wavelength emitted by a bulb that does not match the light spectrum that the plants are accustomed to can yield bad results.

Are T5 brighter than T8?

If the main aim is aquarium growth, then they will be about the same. In this case, choosing tube lighting depends on other factors. One advantage of T5 is that they have more design options. For example, many bulbs give different grow light spectrums to optimize plant photosynthesis.

When looking at it from a light intensity perspective, the T5 is brighter and more powerful.

What is the difference between T5, T8, and T12?

You could achieve the same level of light output with all three types of tubes of different lengths, giving you a bit more flexibility.

The main difference is in their size. T5 tubes are shorter than the T8 and T12 tubes. So they are much easier to install.

T12 tubes, on the other hand, are the longest of the tubes. However, you can’t use them with compact fluorescent bulbs. This is because T12 bulbs are for conventional fluorescent bulbs.

T5 tubes, or mini tubes as they’re often called, are the most popular tubes on the market. They’re the right middle ground between the T8 and T12 tubes, and a great compromise between price, size, and usage. A lot of people consider them the ultimate fluorescents. That's because their size makes them easier to install than T8 and T12 tubes. They can also achieve high light output without too much electrical energy, and the lifespan of T5 bulbs is comparable to T8 and T12.

How do I know what size fluorescent tube I need?

Ideally, all tanks should be provided with “full-spectrum” lighting. This should be the most important consideration when determining the size of your lights.

When choosing a fluorescent tube, consider the diameter, the recommended length, and the bulb type.

T8 tubes are available in several lengths from 24 inches to 96 inches. The most common size is 72 inches. This is a very common size and will fit almost any aquarium.

T5s come in several sizes as well: 2ft, 4ft, 6ft, 8ft, 10.5ft, 13.5ft, etc.


In a nutshell, the smaller the bulb, the more light it produces. This means that, in most cases, you can buy a lower tube size for your tank.