A complete guide to aquarium lighting

A complete guide to aquarium lighting

An essential support system for maintaining the natural development and life cycle of both the fish and the plants that reside in your tank, finding the right aquarium lighting is an important part of creating a good home for your aquatic friends. Buying and installing a lighting system in your fish tank should never be just an aesthetic choice, as the decision you make will impact your fish’s everyday life and health. Having the right lights will, quite literally, light up your fish's life.

As fishkeeping experts, and stockists of some of the leading brands for aquarium lighting, we know that beginner and hobbyist fishkeepers may have a hard time distinguishing exactly which lighting system is right for their tank. After all, lighting requirements change based on species, and with numerous types of lighting available in a variety of colours, temperatures and Kelvin ratings, it can feel a bit overwhelming.

Whether you’re setting up a tank for the first time or looking to upgrade your aquarium to suit your fish's needs, join us as we cover all the tips and advice you need to know for finding the right aquarium lighting for your tank.

What is the best light for your fish tank?

The best lighting for your fish tank will entirely depend on what fish, plants or corals your aquarium hosts. Everything in your aquarium should be built with the residents in mind, right down to the water you’re using, and it’s no different for lights. If you want to find the best lights for your aquarium then you need to ask yourself; what do the residents of the tank need?

To help you find the ‘best’ aquarium lighting for your tank, we’ve split up our recommendations by tank type below, so flick ahead to the section which suits your needs!

Expert note: When shopping for aquarium lighting, you’ll notice products will have mention of the Kelvin rating (K). This refers to the light spectrum (or colour and tone) that a light gives off. Lights with a low Kelvin rating will often give off a warm effect with reds and oranges, whereas lights with a high Kelvin rating will give off cool, bluish tones. It’s important to know what Kelvin rating is as we are going to discuss some of the different Kelvin ratings that are required by different types of aquariums.

What is the best lighting for a freshwater aquarium?

For aquariums that only house fish, the main function of your light should be the recreation of the day/night cycle to avoid any stress on the fish by having too much or too little light. Typically for freshwater aquariums the Kelvin rating will be between 5,500 and 6,000 Kelvin to replicate natural sunlight - perfect for freshwater inhabitants. However, going over the 6,000k can promote algae growth. Algae growth is naturally occurring and healthy in small quantities, but if it grows too much and gets out of hand this can become harmful to fish. For this reason, you should also be mindful of how long you’re leaving the aquarium light on. We will touch on how long you should be leaving your light on later in this blog, so read ahead for more information.

If you’re looking for the perfect freshwater lighting for your aquarium we have this great freshwater tank LED light that is equipped with a balanced white spectrum with a highly tunable Kelvin range to create the best environment for your freshwater fish. Alternatively, try our great Fluval Aquasky 2.0 Light, with Bluetooth controls. It comes with multiple weather effects to choose from, including stormy lightning or dense clouds, to give your fish a taste of seasonal weather that's reminiscent of their natural habitats.

AI Blade Freshwater LED Light Units, from £159.99


AI Blade Freshwater LED Light Units


Fluval AquaSky 2.0 Bluetooth LED Lighting, from £75.98



We also have a full collection of freshwater aquarium lighting systems, bulb replacements and more available for fishkeepers in need of an upgrade, so regardless of your budget, tank size or existing system you can find what you need.

What is the best lighting for a reef tank?

For reef aquariums, the corals require specific lighting conditions which can make them quite complex. Reefs can be found in some of the sunniest places on earth, but water depth completely changes the lighting as it acts like a filter, so you need to be careful to get the level right. 9,000 - 10,000K lighting fixtures produce a good growth rate for soft corals but 14,000K lamps will penetrate the water better. For a coral reef tank, a Kelvin rating of 9,000 - 20,000K will create the best environment for your corals. Blue lights especially are the best to stimulate the coral reef's calcification and replicate a deep water environment.

If you’re looking for a lamp that touches on all of these requirements, then check out our marine LED light unit. It's specifically made to aid the growth of your corals and with a high Kelvin rating and blue-coloured bulbs, this light will help create the perfect, healthy environment for your marine tank. We’ve also got these Red Sea reef LED lights that have been specifically designed to help the growth of corals and are based on years of research. They are 100% reef-safe and are perfect for deeper and wider tanks. However, if you’re looking for something that's directly changeable right from your phone, then look no further than our Fluval Sea Marine 3.0 light, which has a programmable light cycle from sunrise to dusk for an easy and natural light effect for your reef aquariums.

AI Blade Coral Growth LED Light Units, from £159.99

AI Blade Coral Growth LED Light Units


Red Sea ReefLED 160S Light Unit, from £599.00

Red Sea ReefLED 160S Light Unit


Fluval Sea Marine 3.0 LED Lighting with Bluetooth, from £189.99

Fluval Sea Marine 3.0 LED Lighting with Bluetooth

What is the best lighting for planted aquariums?

For a planted aquarium this will depend on the type of plants you’re growing in the tank. Unlike fish, plants have a biological need for sunlight, meaning they require more light than fish do. However, like fish, different species of plants will require different lighting. Below is a quick guide on what the general rule is for low - high intensity plants.

  • Low-intensity plants - 15-25 lumens/litre
  • Medium-intensity plants - 25 - 50 lumens/litre
  • High-intensity plants - 50 and over lumens/litre

Plants use all colours of the spectrum for photosynthesis so it’s important to try and recreate this. Red/blue colours especially will stimulate correlation, which is why white lights aren’t suggested in plant aquariums. Your goal should be to balance the output of red/blue lighting. The general rule is that there should be over 50% red lights and no more than 15% blue lights as plants can absorb up to 75% of the red lights being used, making it more beneficial to them.

If you’re looking for a great set of lights for your plant aquarium, we recommend the AI Prime 16 fresh LED light unit. Featuring 6 different colours, including blues and reds, and a manual Kelvin mode - you can set it to the perfect temperature for your plants, making it the best option for all plants from low to high intensity.

AI Prime 16 fresh LED light unit from £239.99


To help you ensure you give your tank inhabitants the best possible home, we have created a collection specifically designed for marine aquariums, whether you’re completely new to caring for marine life or if you’re looking to upgrade your lighting system, our marine aquarium lighting collection has everything you need to create the perfect home for your aquatics.

Is it okay to use LED lights in a fish tank?

Yes, it’s okay to use LED lights in a fish tank. They actually have many benefits for an aquarium as they are a great way to boost aquascaping and serve as a great cost-effective option. They can even help keep your fish happy. That’s right, coloured lights can actually make your fish happy! They’re a great choice and some would argue an important part of creating a high-quality environment for your fish and plants alike.

Here are some of the ways that LED lights can benefit your fish tank:

  • Green and white lights can make your fish happy - Boats and docks will often use these colours to draw fish in.
  • LED lights can boost plant growth - By helping encourage plant growth by providing the rays required for photosynthesis, LED lights can actually promote better oxygen levels, helping to protect the ecosystem's delicate balance.
  • They are more energy efficient - LED lights don’t cost as much to run as traditional lights do and also tend to last much longer as well.
  • They’re aesthetically pleasing - LED lights are a great way to showcase your fish tank and its inhabitants.

We have a huge collection dedicated to LED lights for aquariums here are Aquacadabra. With some of the best brands for aquarium lighting available, dive into our collection to upgrade your tank with some LED lights that will improve the home of both you and your fish. However, if you already have a T5 or T8 unit and don’t want to replace the whole thing with LED lights, then you can add in these T8 Superfish retro LED bulbs and T5 LED Bulbs which will have the benefits of LED lights but without investing in a whole new unit.

How many hours a day should your aquarium light be on?

Around 10-12 hours of light a day is sufficient for providing your fish and plants with what they need. 12 hours of light and 12 hours of darkness a day is the best for replicating natural sunlight for the aquarium. However, this is just a rule of thumb, keep in mind that algae also loves light and if you see algae growing then it may be best to cut back on how much light you’re using.

Find the best lights for your aquatic friends with Aquacadabra

Whether this is your first aquarium or your fourth, it’s important to find the right lights for your tank's inhabitants. Here at Aquacadabra, we have a wide variety of aquarium lighting available, from LED lighting to T5 lighting, to help you find what you need for your tank.

However, if you still feel like you need more guidance on creating the perfect environment for your fish to thrive then you can contact our experts directly for more guidance and support on creating a safe, and comfortable home for your aquatic friends.