The question of whether running aquarium lights all day and night comes up constantly, especially when talking to newer fish keepers. You walk into a fish store and see countless lights beaming at aquariums all day long. It makes you wonder if that’s okay to replicate at home. In my opinion, no I do not think you should be running your aquarium lights at all times of the day. The goal when setting up an aquarium is often to mimic the natural habitat of a fish, coral, plant, and/or invertebrate. Part of that means providing a day and night cycle for your inhabitants. Besides this, there are a few other reasons why I recommend not keeping your lights on all day, which will be discussed in this article.
Rest Period for Fish
Many species of fish are diurnal, which means they are active during the day and have a rest period at night. Most fish don’t sleep, but they do have periods of rest. This is a time when a fish will wedge itself in between rocks or plants, and remain incredibly still. Their metabolism slows, and it’s time for them to recharge their little fishy bodies. Some fish, like plecos, do this but in reverse, where they are nocturnal and active at night and hide and rest throughout the day. Regardless, providing a dark time for your fish tank will help provide a natural period of activity and rest.
Having lights on all day can cause your fish to stress more because they are not provided a normal “rest period”. In the wild, they spend most of their day foraging and hunting for food throughout the day and will take refuge between rocks and plants at night. Most of us humans use the night to catch up on sleep and rest, and the same goes for many fish species.
Spike in Algae Problems
A constant light cycle increases the chance of your aquarium being plagued with large amounts of algae. Constantly providing a light source for photosynthesis will likely allow different species of algae to wreak havoc on your fish tank. One remedy to fight against algal blooms is actually to cut down on how much light you provide. If you’re fighting an algae problem, take a look at the many ways to Help Remove Algae in Aquariums. Light intensity and duration are both factors to consider when dealing with algae in your aquarium.
Cost & Replacement
If you have one aquarium running, your electric bill probably won’t see a difference if you run your lights all day long. However, once the addictive properties of this hobby overwhelm you, you’ll likely have 3, 4, or more fish tanks set up over a short period. Having your fish tank lights running all day will drive up the price of your electric bill. On top of that, the life of your lights will surely decrease and there is probably an increased chance of your lights burning out the longer you have them running.
Exception To This
There are a couple of exceptions that would allow you to keep your aquarium lights on 24/7. Both of these are related to plants. In the freshwater world, if you keep an aquarium with only plants, and no other animal, you could technically run your lights all day long. I still wouldn’t do it, because your plants likely don’t photosynthesize all day long, but it’s an option.
Second, many saltwater enthusiasts have refugium or macroalgae reactors that have a light running all day and night. Some do it with purpose, and others do it because they’re lazy or don’t have a timer to automatically turn the lights off. However, the idea behind this is to allow macroalgae, whether it’s chaetomorpha or some other species to constantly have a light source in the refugium or reactor which will allow them to grow. Their growth uptakes nutrients like nitrates and phosphates which will aid in keeping algae from growing in the display tank. Keeping the light on 24/7 also helps stabilize the pH in the aquarium. However, from reading people’s experiences, a similar result can be achieved if you simply run your refugium on an inverse cycle to your display tank.
Aquarium Lighting Recommendations
I recommend providing anywhere between 8 and 12 hours of light over your fish tank. Deciding on the specific photoperiod will depend on your specific fish tank’s needs. If your aquarium gets natural light from a window, it will likely not require a 12-hour light period. If your fish tank is in a dark room, it may thrive under 12 hours of light. It is all experimentation to see what works best for your fish tank. Everything is dependent on your plant species, environment, light intensity, and many other factors. Regardless, I do not recommend anything over 12 hours in most cases.
Many aquarium lights now have timers/controllers that work well with your light systems. For instance, the NICREW Saltwater Aquarium Light has a built-in timer that allows you to adjust your photoperiod to your needs. The freshwater counterpart to this is the NICREW SkyLED Aquarium Plant Light, it also has a built-in controller that allows you to adjust different aspects of your light. They can set the photoperiod, and have a ramp-up and ramp-down feature that will mimic sunrise and sunset.
Some saltwater lights have apps that allow you to customize your light intensity, colors, and scheduling. The Ecotech Radion XR15 LED Light is the perfect example of this, but it comes with a high price tag. If that price point is too high, there are cheaper lights such as the NICREW Hyper Reef LED Light that don’t have an app backing them up but still pack a punch when combined with a NICREW HyperReef Light Controller.
If you already have an aquarium light that has neither a controller nor a timer built into it, you can still run your lights on a timer. As someone who is lazy and does not want to turn the lights on and off every day, I invested in a very cheap plug-in timer, similar to the BN-LINK BND-60. This timer is very easy to set up and should take away the chore of turning your lights on and off.
Final Notes
Keeping a steady lighting schedule is great for your fish, and is what should be done to help mimic your aquarium inhabitant’s natural environment. Avoid running your lights 24/7 to help prevent potential algae blooms and for your fish’s health. Whether you do this by switching your lights on/off manually or using a timer/controller to make it hands-off, is completely up to you.
