Tank above lit by Maxlite Life aqua LED.
LEDs are very commonly used in aquariums. Generally, they can grow plants well enough. The main group that finds fault with them are folks that are attempting to grow red plants optimally. Old school T5 users found that they grew better red plants with their specialty T5 bulbs than most commercially available LEDs. LEDs are sleek and more energy-saving, and while most of them grew green plants well, 95% lack the ideal spectrum for stimulating pigmentation in red plants. Many of them grow red plants 'okay' but not to the color saturation of which the plants were capable of - which led to many red plant enthusiasts returning back to using old T5 systems.
For plant centric folks where plant pigmentation and coloration is paramount, there were still better options regarding spectrum selection using speciality T5 bulbs. Most commercially available aquarium LED units lack adequate red and blue spectrum compared to the spectrum that specialty T5 bulbs provided.
This is largely due to the usage of white LED diodes, which generally lack red spectrum. Most white LEDs have a fair amount of blue, and significant amounts of green/yellow, but lack red. A sample 6500k LED's spectrum curve is shown below.
This has changed in recent years though, as we find this group of LEDs do pretty well or growing higher difficulty, colored plant species. The primary difference between them and other aquarium LEDs on the market is that they primarily use RGB diodes and no white diodes. This gives them a higher red/blue spectrum compared to most other aquarium LEDs.
This group of LEDs comprise of ADA solar RGB and its copies.
Tank at top of page: Maxlite Life Aqua gives high red saturation, side view is here:
Same tank, comparison with Chihiros WRGB 2 here:
Side view of tank lit by Chihiros WRGB 2
Photo from Viktor Lantos, Green aqua showing ADA solar RGB.
This group of LEDs use purely RGB diodes to create 'white light'. This also means that they have higher ratio of Red/blue light compared to other LED fixtures while maintaining overall white balance through the use of green diodes. This gives these fixtures very high visual color saturation and contrast for red plants and blue fish. The strong red spectrum is also great for plant pigmentation and growth forms.
Their spectrum profile can be seen below:
Maxlite (above) uses purely RGB LEDs with no white LEDs. All the LEDs in the list above have a similar spectrum profile (as below); with large spikes in red, blue green due to the use of RGB diodes.
This can be contrasted with more regular aquarium LEDs such as the Chihiros X300 and Chihiros WRGB 1 shown below that have a more distributed spectrum. These are decent lights, however, the ones above with pure RGB diodes give higher visual color saturation and contrast and grows red plants better.
Some of the visual differences best seen in these side by side videos:
Comparison of ADA solar RGB and some other fixtures:
Comparison of Chihiros Vivid and other Chihiros fixtures (the WRGB 2 has same spectrum as the Vivid):
The Chihiros vivid is programmable and cheaper (but has fans) while the Life Aqua master pro is dimmable and water proof. The ADA solar RGB is a no frills unit but carries the ADA brand name. Due to exact diodes chosen for their RGB profile; there is also slight differences in visual coloration - the ADA solar RGB and UNS titan have a slightly deeper green tone compared to the Maxlite and Chihiros vivid. ONF Flat one has a more rounded spectrum with less contrast compared to the rest; it may look more 'natural' but less striking.
SBreef lights are another popular option among the technically minded crowd. The fixture is large and bulky, but comes with very high PAR values, considering the fixture cost. This fixture is for folks that favor cheap, high powered lighting, but are less concerned with the aesthetics of the fixture itself which is large and bulky. It is programmable with in-built electronic timer and its spectrum can be tweaked. The main downside of such fixtures is the purplish back light.
Above; Tank by John Eldredge Jr using SBreef (freshwater) lights
Twinstar S series / Chihiros RGB/WRG / Fluval 3.0 /
These are secondary picks compared to the list above. The Twinstar S series works well for smaller sized tanks. The S series has an attractive spectrum, and sleek build. We also like that they do not have fans which are another weak point in many light fixtures. The fixtures are slightly broader than thinner fixtures, but we find that this actually gives better spread in a tank. We think single fixtures work well for smaller standard sized tanks. For 3ft (90x45x45cm) tanks and above, we would recommend having 2 fixtures. The other similar LEDs in this category is the Chihiros RGB.
Above: Twinstar S series by Twinstar Iberica
Above; Twinstar S series, Tank by Luis Cardoso
Above: Chihiros RGB by Michal Zielinski
Chinese black boxes are a nick name for cheap, high powered grow lights mean for indoor farming that you can buy online (usually made/shipped from China). These sometimes come in a more neutral spectrum (white/orange mixed with red/blue LEDs or RGB), though more often they come in just red/blue diodes. These grow plants well and give great bang for the buck. However, finding one that is not just pink, giving an overly purple visual rendition, may be difficult.
There is a widespread belief that 6500K is the optimal value for photosynthesis in planted tank. Is this true?