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 thin. The bulbs are much thinner than the previous fluorescent family: T12 bulbs. The bulb looks a lot like a cigarette lighter.

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 T8 bulbs are sometimes used as T5 but will require a thinner hood. The benefit of using the T8 bulbs is that they allow you to have higher light levels, while at the same time they have lower power consumption.

While the T5 bulbs are better for saltwater aquariums, the T8 tubes can be used in both saltwater and freshwater. They’re 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 5/8th(15 mm) in diameter while T8 are 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; but not all T5 bulbs will fit into T5 fixtures.

T8 tubes, on the other hand, have a length limit of 84 in (2.1 meters). Since T8 bulbs are of a bigger size 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. Since the T5 bulbs are shorter than T8, they do not cast as much light to the plants, so more bulbs are needed to cover the same area.

Another very 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

I talk a lot about T5 and T8 lighting, and more and more folks are shopping for those two types. It helps to know what the differences between T5 and T8 fluorescent bulbs are.

The T5 tube is the big brother of the T8 tube which is slightly taller and more slender than its little cousin.

T5 stands for 5/8'' diameter and T8 stands for 1/2'' diameter.

The T5 and T8 tubes are similar types of fluorescent bulbs therefore they have very similar applications.

They are used for applications where light penetration needs to be relatively shallow, so in cases where light is being used for plant growth and freshwater aquariums.

T5 and T8 tubes are almost always used for planted aquariums or situations where lots of medium to high intensity lighting is required.

Deep, natural coral reefs and plant aquariums are good applications for T5 and T8 lighting.

The T5 is typically going to be more efficient and more powerful than T8, but the size of it it's makes it more difficult to work with in shallow situations.

T5 and T8 light tubes are commonly used in retail stores to help improve the color of water plants in the aquarium portion of the store.

T8 tubes are used in window mount fixtures for fish only aquariums.

T8 vs T5

Which is better for planted aquarium?

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 basically have two types of bulbs to choose from. And they are T8 and T5. Each of these bulbs work well and will do the trick, but they each have their pros and cons.


You probably have seen these bulbs at the pet stores. These bulbs are 5/8” in diameter. Now, these 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.

If you plan on floating plants, using this bulb is a good idea. At least the plants are not sitting in the dark. There is also a good spectrum for plant growth.

The bad thing is that you may need a lot many 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, popularly as 8–16 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.

The 8–16 tubes also run at a lower wattage compared to T5 tubes. Wattage is a measure of the amount of light produced. T8 tubes have a wattage of 24W to 32W whereas the T5 tubes run at 16W to 21W.

This may lead you to believe that the T5 tubes are more efficient. But the 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 of time.

Which Bulb Fixtures Costs More?

Reputable marine aquarium stores won’t carry light bulbs that are damaged or have had their packaging compromised. It’s a sure sign of an imposter.

Be aware of the color temperature that you choose. A color temperature of daylight or higher is best for fish that need color stimulation.

Choose the right wattage for the tank. A 15-watt strip should be fine for a tank that is 24 inches long. Equip yourself with a good wattage calculator before purchasing any lights.

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It’s because the more options you have, the easier it is to get where you want to go and the faster you have reached your destination.

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Why Converting to LED Beats Fluorescent T5 And T8 Tubes

One of the most commonly asked questions in the aquarium world is, “Should I switch from fluorescent tube lights to LED lights?”

The answer isn’t that simple and it’s not a black or white decision.

To help you make a decision, let’s try to answer each of the possible questions one by one.

Frequently Asked Questions

Everyone wants the best for their plants, and there’s no shortage of advice on this subject. With so many options out there, how do you know who’s right and who’s wrong?

There’s one thing I will say about “the best”: it’s subjective to the situation. What works for one grower may not be a good fit for others.

It’s also important to note that the best grow lights for one situation (or plant) won’t always be the best fit for another grower (or plant).

But if you’re only going to invest in a few products, you want to make sure that you invest in the right gear and products to get your plants to where you want them to be.

In this article, I’ll do my best to address the most common questions and concerns regarding the best lights for growing cannabis.

Let’s dive in.

Are T5 and T8 bulbs interchangeable?

When it comes to aquarium or terrarium lighting, T5s and T8s are two of the most widely used florescent bulbs. People often ask whether they can use T5 bulbs in their T8 fixtures and vice versa. My answer is an absolute “Yes”!

While T5 and T8 bulbs have the same electrical characteristics and fit a common light fixture, they are not 100% interchangeable.

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. Here we explain why T5 and T8 bulbs are not interchangeable and how you can take advantage of using both types of bulbs in the same light fixture.

Are T5 brighter than T8?

If the main aim is aquarium growth and the result is 10cm of growth of a stem plant per day, 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, there are many bulbs that give different grow light spectrums to optimize plant photosynthesis.

When looking at it from an efficiency perspective, the T5 is more efficient since it is more powerful per watt.

For the same or higher brightness, the bigger T5 takes less space. The T8 needs to be paired up or in multiples to get the same brightness. This increases the cost of the electricity bill.

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 length 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. In fact, a lot of people consider them the ultimate fluorescents. Why, you may wonder?

Because of the following reasons:

Their size makes them easier to install than T8 and T12 tubes.

They’re compatible with compact fluorescent bulbs, so you don’t have to deal with the hassle of fluorescent starters.

They can achieve high light output without too much electrical energy.

The lifespan of T5 bulbs is comparable to T8 and T12.

High quality T5 tubes are as energy efficient as the T8 or T12 tubes.

How do I know what size fluorescent tube I need?

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

The size depends on the tank length based on the following:

25W = up to 2ft; 35W = up to 4ft; 55W = up to 8ft; 75W = up to 12ft, etc.

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.

While T8 tubes are still popular, T5 is the more advanced lighting. It is 2 ‘ smaller than T8 and can be snaked through the aquarium easier without burning the fishes. The aquarium looks brighter with the same wattage.

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.