When it comes to equipment for aquariums, much of the focus is on the filter, heater, etc. There’s not much discussion on aquarium lights.
Although some may not deem it important, aquarium lights do play a significant role in maintaining a healthy ecosystem.
A question that frequently pops up is how long should a fish tank light be on?
Let’s find out the answer to that question and also learn some additional things about aquarium lights.
Why is Aquarium Lights Needed
One of the reasons is pretty straightforward: lights allow you to see your aquarium in all its glory.
After all, the whole concept of aquariums is to be attractive to the eyes. Bright lights not only illuminate your various décor, but they also bring out the best colors of the main attraction: your fish!
For aquariums with live plants, lights are essential as a source of energy for photosynthesis; through this process, plants can convert CO2 into oxygen, improving the health of your aquarium.
Plants with red color in particular need intense lighting to get the energy they need.
Aquarium lights also give you the ability to mimic the day/night cycle in nature by turning it on and off periodically. We’ll explore more into this later in the article.
Should You Keep Aquarium Lights on All the Time
So, how long do you keep your aquarium lights on? Before we look at the right answer, here’s a wrong answer: all the time.
You should not leave the lights on all the time as it causes various issues for the inhabitants of your aquarium.
Like most animals, fish too have a circadian rhythm, which means they have an internal ‘body clock’ that indicates whether it is day or night.
Furthermore, the circadian rhythm in fish is sensitive to light, which means you can seriously mess it up with constant light.
Fish do enter a sleep-like restive state at night. Owing to the fact they have no eyelids and their pupils don’t contract, they cannot control the light hitting their retinas. So light deprives them of their sleep – imagine trying to sleep in a brightly lit room with your eyes open.
Light also stresses the fish, especially if they have no dark hiding spots to take refuge from it. You may have seen fish scattering as soon as you hit the switch.
Also, fish need a proper aquarium light cycle to regulate their hormones and other bodily functions.
Here’s another issue with constant light: your plants aren’t the only things that thrive in light – algae can grow unchecked with a near-unlimited source of energy. The last thing you want is for your aquarium to be covered in green slime.
How Long Should Aquarium Lights Be On
Let’s look at how long aquarium light should be on, now that we know that keeping it switched on all the time is a bad idea.
While the exact number depends on various factors, generally, a fish tank light should be on for 8-12 hours per day; it should be dark for the rest of the hours, preferably totally dark.
This varies according to fish species; for instance, tropical fish (and plants) are used to getting 12 hours of sunlight in the wild, so 10-12 hours would be ideal for them.
If you don’t have tropical fish, you can reduce the aquarium light hours per day; if you don’t have plants, you can reduce the number even further, down to 6-8 hours.
By reducing the number of hours, you are saving on your electric bill; you also prevent the excessive growth of algae.
Remember to consider the ambient light, such as sunlight or your room lights; it is best if it is totally dark once you switch off the lights – this period of total darkness is more important for the fish than having the lights on.
Also, make sure you turn the lights on/off at the same times every day – this will allow the fish to maintain a proper circadian rhythm.
How Long Can Aquarium Plants Go Without Light
As we have seen above, aquarium plants do well with 8-12 hours of light every day. But what would happen if the lights go out – how long will they last?
Good news is that they can last for a pretty long time without their only source of energy – healthy plants can survive for about 5 days without light; some can even last for more than a week.
Remember that even if the aquarium lights go out, there will be some amount of ambient light, whether it is from sunlight or the room’s light, which will sustain the plants to some extent.
What to Look For in Aquarium Lights
First, you should determine the type of light you are going to use; your options are incandescent, fluorescent, or LED.
The problem with incandescent bulbs is the heat they emanate; it can increase the temperature of your tank, often unevenly.
LED lights are the most expensive, but they are also the most suitable due to their durability and virtual absence of radiated heat.
Next thing you would want to look for is the light spectrum – you can pick from RGB (Red, Green, or Blue).
Red and blue are good for photosynthesis; blue alone will be a cool ‘dark’ light. White light spans the entire spectrum and will brighten up your tank nicely.
Go for lights that have an even distribution of intensity, which will make it look much more appealing.
Some aquarium lights come with integrated timers, which will save you a lot of trouble – imagine turning the lights on and off at the same time each day; you are bound to forget it some days.
It’s also great if the lights have a dimming function – it looks so much better, and is more natural, for the lights to come on and go off slowly. Lights turning on abruptly can be stressful for fish.
Lastly, any decent aquarium lights should have moisture protection considering it is near water all the time.
Conclusion
I hope by now you have a good idea of how long to leave aquarium lights on.
While the actual number may vary between 6 to 12 hours, one thing is for certain: you should not leave it on all the time. Doing so can affect the health of your precious fish.
An aquarium light with an integrated timer and dimming function will be excellent for your fish tank.
With good periodic lighting, your aquarium will be a great visual spectacle that also respects the health of its inhabitants.
Thanks for reading.
