Spectrum of radiation at different depths: Spectrum of radiation at different depths:
The spectrum of radiation changes as we move from the surface to the deeper parts of the ocean. Red and yellow wavelength are irradiated within the first or two meters, and green and blue wavelength penetrate much further. At depths below the 10 meters, only blue bands are visible. Consequently, an illuminating device whose spectrum is equivalent to that of daylight at the target depth has to be selected.
Types of lighting: Types of lighting:
Diversas luzes para aquários réefs marinhos, incluindo metal halide (MH), fluorescente T5 (T5F), luzes de estado sólido (LED) e sistemas híbridos. Metal halide lighting has been the most used in the past, but it has a high energy efficiency and high temperature. T5 fluorescent lighting is more power efficient, but there is not enough PAR for SPS coral. LED lighting is the most energy-effective and flexible, by changing the spectrum and strength of the light. Hybrid systems integrate types of light to enable the advantage of both.
PAR levels for different types of corals:
PAR (Photosynthetically Active Radiation) represents the amount of light used for photosynthesis. Different types of corals have different PAR requirements.
SPS (Small Polyp Stony) corals require higher PAR levels, ranging from 250 to 450 (μmol/s/m²), while LPS (Large Polyp Stony) corals and soft corals require lower PAR levels, ranging from 50 to 150 (μmol/s/m²). It is important to measure the PAR levels in the aquarium and adjust the lighting accordingly to ensure optimal growth and coloration of the corals.
Nevertheless, the desired PAR (i.e., PAR amount) is dependent on the coral species, reef depth, and from the ecology of the physical environment such as water quality and coral population density. For example, SPS living in shallow waters near the surface of the sea require a very high amount of light, while those living in deeper waters can tolerate a lower amount of light. Depth of your tank is also a factor to be explained, as PAR is decreased the deeper water it is penetrated by lights. So it follows that photosynthetic organisms, like corals, at the bottom of the tank will get less PAR than canopies covering species at the top. In order that all of your corals have adequate light they may need to be repositioned or lights may need to be strengthened.
There are several tools available for measuring PAR in marine aquariums. Here are a few options:
1. Apogee MQ-200 PAR Meter: This is a popular PAR meter among aquarium hobbyists. It has a range of 0-2000 µmol m⁻² s⁻¹ and comes with a handheld sensor and a data logger. Apogee MQ-200 Quantum-Meter
2. Seneye Reef Monitor: This is a monitoring system that measures PAR, as well as other parameters such as temperature, pH, and ammonia. It has a range of 0-2000 µmol m⁻² s⁻¹ and connects to your smartphone or computer for easy data tracking. Seneye REEF V2 – aquarium monitoring system
3. Neptune Systems Apex AquaController with PMK PAR Monitoring Kit: This is a more advanced monitoring system that includes a PAR sensor, as well as other sensors for measuring temperature, pH, and ORP. It has a range of 0-2000 µmol m⁻² s⁻¹ and connects to your Apex controller for easy data tracking and control. Apex – PMK :: PAR Monitoring Kit
There are also various online calculators available online to help you determine the PAR levels in your reef tank. Here below one example :
1. Coverage/PAR for current control point : Aquaticlog Keep in mind that these calculators provide estimates and should be used as a guide. It’s always best to use a PAR meter to get the most accurate readings for your specific tank and lighting setup.
Choosing the right lighting for your tank is essential for the growth and sustainability of the corals. Understanding the spectrum of radiation at different depths, types of lighting, and necessary PAR levels for different types of corals can help aquarists make informed decisions. It is important to measure the PAR levels in the aquarium regularly and adjust the lighting accordingly to ensure optimal growth and coloration of the corals.
If you want to document yourself, this is the book for you: The Manual of Marine Invertebrates: A Comprehensive Guide to the Care and Husbandry of Invertebrates in a Home Aquarium:
The book includes a section on light and PAR measurement.
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