Metal Halide
Two 150 watt HQI Metal Halide lights over a 30 gallon tube tank.
Metal halide lights both HQI and HID get extremely hot, and can give you a 3rd degree burn in no time if you were to touch it after it has been on a few minutes. You must be able to provide lots of ventilation in the form of auxiliary fans to help kept the tank from getting to warm. If metal halide lights are mounted in a canopy, you must also mount auxiliary fans.
Metal halide bulbs require special handling when replacing the bulb, never touch a bulb with you bare hands, always use a clean cloth to handle the bulbs. Oils on your fingers can damage metal halide bulbs. Metal halide lights above an aquarium make a stunning display. With surface agitation, metal halide lights give the tank a shimmering light effect similar to the sun shining through a crystal clear lake. Normally one 150 or 175 watt light is good enough to cover a 24″ x 24″ (60 cm x 60 cm) footprint with a depth of 24″ (60 cm) or less. If your tank is 30″ to 36″ (75 cm x 90 cm) tall, you may want to consider a 250 watt light.
Compact Fluorescent
Three 65 watt Compact Fluorescent Lights over a 60 gallon cube tank.
Compact Fluorescent Lights (CFL) are very popular choice with aquatic plant hobbyist. While they can produce a lot of heat, they are much cooler than metal halide lights. In some cases you many need auxiliary fans with these lights, especially if they are mounted in a canopy.
These bulbs vary in wattage, depending on the length of the bulb. For a standard US 10 gallon 20″ (50 cm) long tank the bulb is usually 36 watts, for a 24″ (60 cm) tank they are either 55 or 65 watts, for a 36″ (90 cm) tank they are 96 watts. I normally recommend one or two bulbs per 12″ (30 cm) of width of the tank. CFLs are generally good enough for tanks 24″ (60 cm) or less in height.
T5 High Output Retrofit Light
T5 High Output (T5 HO) Fluorescent are becoming very popular in the freshwater aquarium plants hobby. T5 HO lights are very compact, put out a lot of light, and are cooler to operate than metal halide. They may require auxiliary fans with these lights, especially if they are mounted in a canopy. These bulbs vary in wattage, depending on the length of the bulb. Bulbs for a 24″ (60 cm) long aquarium are 24 watts, for a 36″ (90 cm)tank they are 39 watts, for a 48″ (120 cm) tank they are 54 watts, and for a 60″ (150 cm)tank they are 80 watts. I normally recommend two to four bulbs per 12″ (30 cm)width of the tank. T5 HO are generally good enough for tanks 24″ (60 cm) or less in height.
Catalina Aquarium’s 15 inch LED light system
LED (Light Emitting Diode) are the newest lighting system for the aquarium hobby. One advantage these lights have over the others listed above is they produce very little heat. They are also the most expensive option right now. They are gaining popularity and their application over nano tanks may be the best option. Catalina Aquarium ( one of recommended aquarium supplies online) offers a 15″ LED lighting fixture that has 180 LEDs that use only .3 watts each for a total of 54 watts. They say it puts out the same amount of light as a 175 watt metal halide. These lights are an option if you don’t want to deal with the heat, and are willing to pay the extra cost.
The color temperature of the bulb can make a difference on how well your plants will grow, and take up nutrients. For freshwater the ideal bulbs fall in the 5500K to 6700K range. 10000K bulbs will also provide fairly good growth and appearance. Higher K bulbs will normally look bluer and this often makes green plants look pale yellow. Actinic lights should be avoided, as they make plants look yellow.
Before you go to aquarium supplies online and buy new types of aquarium lighting system like this Nano Aquarium Lighting Arc Pod 9w by Arcadia and add it to your freshwater tank, it is recommended that you do several water changes to try and reduce the amount of nutrients in the water. This can sometimes prevent excessive algae growth. Place your light on a timer so the lights go and off even when no one is a home. Now let there be light!
