This comparison takes into account the initial setup, and continued cost of lighting a beautiful aquarium over a 1-2 year period.   It will show that LED aquarium lights are actually the cheapest to keep and maintain.

Currently fluorescent light fixtures (VHO) are the least expensive to purchase while LED is the most expensive with Metal Halide (HQI) somewhere in the middle.

The first thing to be considered is bulb replacement.  The VHO and HQI bulbs need to be replaced every year, while the LED lasts 7 -10 years.

The second consideration is heat.  You might not think of heat when referring to lighting, but heat is an issue for aquariums.  HQI produce so much heat that chillers are often used to help lower aquarium temperatures.  This often requires an extra pump to help run water through the chiller itself.  VHO fixtures in general do not produce enough heat to require a chiller but some of the high output fixtures that use ballasts, will also produce heat.  LED fixtures have little to no heat, so no heat transferred to the aquarium.

The last consideration is power.  Electricity runs all of the lighting fixtures, but by far the most energy efficient is the LED, then the VHO, and then the HQI.

I myself had an HQI fixture on my 260 gallon fish tank.  I switched to standard (VHO) bulbs, and then to LED, which I currently use and like.  My electric bill dropped by half, from a budgeted amount of $900 / month, to a current $450 /month.  I eliminated the chiller, and two sump pumps used for the chiller and skimmer.

One additional aspect to consider other than cost is the effects on the aquarium inhabitants.  For instance, the VHO bulb gives an even light distribution along the entire bulb, giving the tank a constant light throughout the entire aquarium.  The HQI gives a more concentrated beam of light, more like the sun, has a more natural shaded area and a shimmer effect on the surface of the water.  LED's also give a shimmer effect to the surface of the water.

All together, the overall benefits of aquarium led lighting make up for initial cost in future savings.  By the time you add in the cost of replacing bulbs every year, extra pumps, chillers, and the electricity it costs to run such devices the clear winner is the LED fixture.

Thank you for reading my article, I hope it helps you in choosing the right lighting fixture for your aquarium.