Leds: an Introduction

LEDs are the new ‘IN’ in the lighting world and so is in our hobby where lighting is an essentially important. Be it reef, planted tanks or simple fish setups, light is needed everywhere.

We have been using CFLs, PLLs, metal halides, T5s, T8s, T12s etc for our lighting needs but after LEDs have hit the market, they seem to be the best lighting solution. Let’s have a look at some of their pros and cons -

PROS-

* Very low electricity consumption.

* Very high light output.

* Long lasting components.

* Economical in the long run.

* Very small in size.

* Latest in technology.

* The wavelength of the LED can be customized according the need by the manufacturer.

CONS-

* High initial cost.

* The cost of other components needed to make a LED light unit.

* The heat produced.

* Very fragile. Care must be taken when installing.

And as we all know, hobbyists need a single reason to start something new ;) And we have so many.

PAR

Before starting the discussion on LEDs I’d like to explain one thing. PAR - which stands for Photosynthetically Active Radiation.

We have been measuring the lights in our tanks in Watts per gallon.

Let’s just assume there are two tanks of same capacity, say 10 Gallons, but their heights are different. One is 14” in height and the other one is 9” in height. If we put the same light at the same height over both the tanks, would light reaching the bottom of the tanks be the same ??

NO… It would never be the same. So, its time we stop using WPG in our fish-talks.

Let’s discuss PAR in a little more detail now.

Light intensity can be measured in lux, which is the intensity as perceived by human eyes. Or, it can be measured in PAR units, which is the intensity as perceived by plants. PAR stands for “photosynthetically active radiation” - the radiation (light) that is used by plants for photosynthesis. The units of PAR are micromoles of photons per square meter per second. So, a PAR of 1 is one...