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Blue, Red, White Lights—The Best Spectrum For Aquarium Plants

Blue, Red, White Lights—The Best Spectrum For Aquarium Plants

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Many planted tank owners often overlook the visible light spectrum and how it affects their plants’ growth, but instead, concentrate on the not so critical kelvin temperature of a bulb.

Why should you care about the lights spectrum and not the Kelvin temperature, you ask…

…because a bulb temperature will only tell you how bright or dim the lamp is, but not how that light will aid in photosynthesis.

What you want is a bulb with more robust red and blue lighting for your plants, and moderate green, orange, and yellow spectrums for a balanced visual output.

A mix of blue and red lights helps in the leaf and stem development because they are readily absorbed. While green light, which is mostly reflected, is more beneficial for your vision.

It only means that how bright your bulb is has more to do with the light output in reference to the human eye, with brightness being maximum in the green spectrum.

But that is not to say that the green spectrum is not useful to plants.

That said, if you own or desire a planted fish tank, this post will take your through everything you need to know about aquarium lights and the light spectrum.

For your aquarium light schedule, please see this guide, and for LED aquarium lights, read this article instead.

What Color Light Is Best For Aquarium Plants?

Colors on aquarium plants pop more when there are stronger red and blue lightings, but there should be enough green, orange, and yellow spectrums as well to give a balanced visual output.

As I have mentioned, aquarium plants absorb red, and blue lights within the visible light spectrum more than any other intensity, thus blue and red color bulbs make the best alternative for planted fish tanks.

Even with a full spectrum white light bulb, your aquarium plants will only utilize light that is absorbed, the rest of the spectrum is only useful for your fish tanks visibility and fish colors.

So next time you go out for your aquarium bulb replacement, consider getting an RGB LED bulb for you fish tank instead of the normal white bulb, but make sure the light has a quality diode rest you end up with a pricey crap-job.

Is Blue Light Good For Aquarium Use

Now that we’ve determined blue light is good for aquarium plants, what about your fish?

Well, blue LED lights, which are most times sold as moonlight bulbs, are good for aquarium fish. They produce a calm blue hue that allows your skittish fish to venture out and feed at night, while also letting fishes that are only active during the day to get the much-needed rest.

With moonlight bulbs, you get an awesome display of your fish tank as well, without having to deal with the hassles of using a flashlight.

So, if you are one to host dinner parties, then consider getting moonlight bulbs just don’t leave them on all night as they are one of the perfect spectrums to help algal growth.

What about fish colors?

As you would expect, you will be able to see your nocturnal catfish better, plus blue light will actuate your fish colors, especially those green, blue and red shades.

Even so, a white light will show some shades of blue and fluorescent colors better, while a magenta is ideal for bringing out the best in red-colored fish.

The blue light will work magic for plant pigmentation best though, meaning most of your red plants will grow ‘redder’ when exposed to strong red and blue spectrum light, especially if coupled with nutrients dosing.

Is Red Light Bad For Fish

For the most part, red lights are not bad for aquarium fish.

Red bulbs are actually quite helpful since you can use them to observe shy nocturnal fish at night without stressing them.

There is a common belief among fish keepers that like reptiles, fish cannot see red light. And while the argument does not hold any fact to it, water does absorb red light readily than blue light, meaning using red bulbs will encourage bottom-dwelling fish to come out and play either way.

This hack is especially helpful when keeping timid loaches like kuhli loach, catfish or plecos.

And just to reiterate, red light is also used by aquarium plants, particularly to stimulate taller growth and flower development in the less than handful plants that blossom in an aquarium environment.

The light will encourage pigmentation in red plants as well.

Unfortunately, you can only use red lights in moderation because algae use the red frequency to conduct photosynthesis, and only using a little of this spectrum will slow the algae growth.

White or Blue Light For Aquarium?

Although full-spectrum white bulbs are the most common for aquarium use, they are not always the best alternative. Yes, they are bright and will probably illuminate your aquarium better than RGB bulb, but in terms of plant growth, they are not as effective.

Oh the other hand, blue light bulbs will both support your plants and will also light up your tank, even at night where using white bulbs is not feasible.

Moonlight blue bulbs are calm and help nocturnal fish feed at night while the rest of your tank inhabitants sleep.

Moreover, it is better to purchase RGB LED bulbs when you cannot access blue moonlight bulbs from your local fish store.

The red spectrum is quite useful to plants (as we have already seen), sometimes even more than blue and green light in shallow tanks. But because red light is easily absorbed by water, the green and blue spectrum in a multicolored bulb take over in deeper fish tanks.

Given that background, if you must purchase a white bulb for use in your aquarium, please stick to full-spectrum bulbs that include the blue, red, and green frequencies.

Do Aquarium Plants Need Special Lights?

No, aquarium plants do not need special grow lights to thrive in a fish tank. But depending on what you consider special, it is perfectly OK to get premium aquarium lights when operating a high tech planted tank.

On the flip side, It is not advisable to use regular off the shelf lights for a planted fish tank. Instead, go for RGB LED lights or white full spectrum bulbs.

Plus make sure the lights are from a reputable manufacturer where quality is assured. With LED bulbs, you’ll especially want to make sure the light-emitting diode is top-shelf quality.

Instead of getting an LED light fixture with a poor quality diode, I’d rather you purchase a regular T5 fluorescent bulb.

Can You Use Grow Lights For Aquarium Plants?

Whether grow lights can be used in planted aquariums is a really tricky question to give a straight answer to. Even so, it a well-known fact that all plants need light to grow, including aquatic species.

Aquarium plants do exceptionally well with red, blue, and green light.

Therefore, if you have a grow light that has blue, red, and green frequencies, I do not see why you cannot use them in your aquarium; just make sure you use quality LED bulbs.

Eddie Waithaka

Resident Content Creator and Marketer at AquariaWise who talks about aquariums and fish and aquascapes a lot.

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