As there’s so much choice when it comes to fish tank lights, it can be confusing to work out which replacement light tube you need. That’s why we’ve put together this simple lighting guide. Here, you can read up on the differences between each type of aquarium light.
There are three main types of fish tank lights: T8 bulbs, T5 bulbs, and LED bulbs. Historically, some large aquariums also used metal halide bulbs, but these aren’t energy-efficient and are pretty rare now.
Today, most tanks use LED bulbs. These are the most energy-efficient and tend to last longer. However, some older tanks do still need T5s or T8s. But how can you work out which you need?
Working out which fish tank light you need
The easiest way to work out which aquarium light you need is to check your tank handbook. Don’t worry if you haven’t got this, though. You can also work out what type of bulb your tank uses by measuring the bulb’s diameter.
- T8 bulbs measure 26 mm (1 inch) in diameter.
- Meanwhile, T5 bulbs and LED bulbs measure 16 mm (0.6 inches) in diameter.
- You can tell the difference between T5s and LEDs by checking for diodes. If your bulb has diodes, like the ones in the photo, it’s an LED. If it doesn’t, it’s a T5.
T5 and T8 bulbs
Many tanks use T5 or T8 fluorescent tubes, and it’s easy to confuse the two. As a result, our customers often ask the same question when shopping for T bulbs:
What’s the difference between T5 and T8 bulbs?
The short answer is that T5 and T8 bulbs are different sizes and therefore fit different fish tanks. They’re not interchangeable.
Bonus Tip
Fluorescent tubes don’t last as long as LEDs. They dim over time and change in wavelength, which can encourage algae growth. You should replace T8 and T5 bulbs every 6–9 months to ensure optimal light output.
T8 bulbs
T8 bulb output depends on the tube length. For example, a 590 mm Juwel T8 bulb has an output of 18 watts. Meanwhile, a 1,047 mm T8 bulb has an output of 38 watts.
Years ago, T8 fluorescent bulbs were the traditional lighting choice for aquariums. Then, manufacturers produced T5 bulbs, which have a higher output and offer better lighting for plant growth and coral tanks. And now, LED bulbs have superseded both T8 and T5 bulbs.
However, some manufacturers still produce T8s in different styles with varying Kelvin ratings for older aquariums.
T5 bulbs
Fishkeepers have illuminated their tanks with T5 bulbs since the nineties. These brighter versions of T8 bulbs are 40% smaller and have a much higher output. This means they burn with better intensity (between 24–80W) and provide a more powerful light source for marine creatures.
Like T8s, T5 output varies depending on the length of the tube. While a 590 mm Juwel T5 bulb has an output of 28 watts, a 1,047 mm T5 bulb has an output of 54 watts.
LED bulbs
As the most modern lighting for fish tanks, LED fish tank lights are far more efficient than both T8s and T5s. All modern fish tanks use these future-proofed bulbs.
Not only do LED aquarium lights have a lower consumption rate, but the light emitted is usually better quality than the light emitted from T5s and T8s. Therefore, LED fish tank lights are especially ideal for aquatic plants, corals, and reefs.
Though LED lights are more expensive than T8s and T5s, they tend to work out cheaper over time because they use less electricity and usually last for years.
If you have an older fish tank, you can still upgrade your aquarium lighting to LED. Follow the simple steps in this blog post to complete your upgrade.
You can also learn more about aquarium lighting in our aquarium lighting guide for Juwel tanks.
About Warehouse Aquatics
The Warehouse Aquatics mission is to offer the most choice at the best prices when it comes to your fishes’ wellbeing. We use the products on our website ourselves and are well-versed in all things fish, so we can give you all the advice you need. We’re not just here to sell aquatic supplies. We’re also here to guide you through your journey as a fish owner and enthusiast.
As a small team, we love to hear from our customers, so please do join the Warehouse Aquatics social media community. We’re always up for a chat, and we’d love to share your aquarium photos with our followers.