What lamps are used to illuminate the aquarium.
To be continued…
Compact fluorescent lamps (CFL) – The operating principle of CFLs is the same as that of traditional fluorescent tubes: under the influence of electricity, mercury vapor begins to generate ultraviolet radiation, which the phosphor applied to the inner surface of the bulb converts into visible light. Such lamps have high efficiency (luminous efficacy is 80-100 Lm/W), a good color rendering index (CRI), and a long service life. There is one fundamental difference: miniaturization. There are also lamps with a built-in reflector that modulates directional light. For a more even illumination of the aquarium, annular CFLs are of certain interest.
An energy-saving compact lamp both works much longer and consumes much less power. A long service life, during which the luminous flux drops insignificantly, unlike high-power lamps, which do not exceed compact ones in luminous efficacy. The ability to use with electronic ballasts that allow light control (dimming). Compact lamps are the most optimal choice for illuminating medium and large groups of plants. The disadvantage of these lamps is the higher cost of the system, but it pays for itself quite quickly – two compact lamps cost less than the more frequent replacement of conventional fluorescent lamps.
The color characteristics of a lamp’s light are usually reflected in its alphanumeric index located on the body or packaging. Usually, this is the last group of three digits, the first of which (8 or 9) reflects the color rendering index (the higher it is, the lower the color distortion), and the other two reflect the color temperature: “27” corresponds to 2700K, “30” to 3000K, and so on. Regarding the advantages of CFLs — Where there was one linear 18 W lamp, you can install two 24 W compacts; — where there was one 30 W, you can put two 36 W ones; — and in place of a 36 W linear fluorescent lamp, you can install two 55 W compacts! And as a result of such an addition or replacement – an abundance of light for your plants!
Krypton lamps. To reduce the rate of evaporation of tungsten from the incandescent filament, incandescent lamps are filled with gas. In cheap lamps, a mixture of nitrogen and argon is used; in more 
expensive ones, instead of argon, krypton is used, which has lower thermal conductivity, or xenon, which has even lower thermal conductivity. If the lamp is halogen, then iodides make up about 1%, and everything else is inert gases. In all other respects, these lamps are still the same incandescent lamps; they differ from conventional lamps in having a reduced mushroom-shaped bulb.
Progress has also affected the glass from which lamp bulbs are made. One of the latest trends is the use of neodymium glass. Many companies produce such lamps, indicating that these are lamps for plants (Osram Flora, Chromalux Neodym, Eurostar Neodymium, etc.). Neodymium and other rare-earth elements are added to the glass to absorb the yellow-green part of the spectrum. At the same time, the visible coloration of plants improves, and the eye perceives the lighting as brighter.
However, this lamp does not produce more light than a regular incandescent lamp. Its entire effect is purely visual. This lamp does not produce any ultraviolet radiation (just like a regular incandescent lamp). These are 40, 60, 100 W incandescent lamps filled with the inert gas krypton. For aquarium plant lovers, it is important that these lamps produce more orange rays than regular lamps.
Halogen lamp (tungsten-halogen) – differs from an incandescent lamp in that there is a halogen (usually iodine) in a gaseous state inside the bulb. As a result of the halogen cycle, tungsten atoms that have flown off the filament return back. Due to this, the service life, luminous efficacy (about 25 lumens/watt), and color temperature are increased. By the end of its service life, the bulb glass does not darken due to settled tungsten atoms from the filament. A halogen lamp seems to be a good alternative to replacing standard incandescent lamps in aquarium lighting, but nothing more.
Currently, many companies produce beautiful hanging fixtures for aquariums with halogen lamps (due to the high temperature of the halogen lamp bulb, 250°C and above, liquid is not allowed to get on the lamp itself). Double-bulb halogen bulbs are additionally coated with a light reflector, which eliminates the need to install a large additional reflector in the fixture.
The use of halogen lamps is interesting; their powerful directional light (an angle of 10-15 degrees) forms distinct shadows of fish and decorations on the bottom of the aquarium, making them more embossed and dynamic. But due to high temperature heating, it is better to use them for demonstration (temporary) purposes. The disadvantage is a relatively short lifespan – approximately 6,000 hours.
LED lamps. Due to their economy and durability, LED aquarium lighting systems are attracting more and more attention from both aquarists and aquarium equipment manufacturers. Perhaps the biggest obstacle standing in the way of developers of LED equivalents to regular high-brightness lamps is device overheating. Actually, LEDs do not heat up as much as incandescent lamps. But the temperature is higher the more LED chips are combined in a single light source.
At the same time, heating provokes a decrease in chip efficiency and a reduction in lamp lifespan. LED equivalents last longer than CFLs, but truly bright models until recently were large in size and incompatible with standard sockets. Another promising innovation — organic light-emitting diodes (OLED) — is still too expensive to manufacture and has a number of other disadvantages.
Lamps in the form of flexible strips designed for internal aquarium backlighting are also produced. It is a self-adhesive strip with LEDs mounted in a waterproof housing. The lamp is very easily attached to any surface and allows you to create interesting lighting effects, enhance water color, or provide mild night lighting for the aquarium. This model can be used in both marine and freshwater aquariums and is intended only for their additional lighting.
The use of LEDs significantly simplifies and cheapens the lighting of aquarium setups. 20 watts of light power consumes 1 watt of electricity. The assembled device takes up virtually no space. The service life is endless (with reasonable operation). To set up LED lighting in an aquarium system, it is enough to have a waterproof strip with LED assemblies and an adapter. It is most appropriate to use 240-watt adapters (enough to power 20 m of LED strip). Depending on the dimensions of the aquariums, the strip is cut into pieces, which are connected in series with each other by wires.
Night light. At the same time, do not forget about the night – this is about 12 hours! Most natural environments are not in total darkness at night; they are illuminated by moonlight. Lunar LEDs as night lamps for the aquarium are the best source of night illumination. Such lamps for aquariums create lighting with the ability to observe the nocturnal behavior of organisms without disturbing their peace, contributing to good health and natural spawning behavior.
Lunar LED lighting has too low an intensity to be evaluated on the Kelvin scale. Usually, this is blue light. There are also white lunar LEDs to simulate full-moon illumination. Aquarium moonlight lamps are suitable for lighting any aquarium if you are interested in fish breeding.
Light sources in the aquarium. Metal halide lamps, T5 lamps.
Light sources in the aquarium. Fluorescent lamps. 
