Help building Hanging LED

[efzichal]

I have a 29 gallon Aqueon and currently use the Aqueon LED Light fixture. However I am looking to upgrade because its not doing a great job, especially since it only adequately lights the middle of the tank. I would like to do the hanging LED over the tank but I have one major question
I have been searching the internet for LED fixtures. How to you determine the length needed because they come in so many different sizes?

Thanks

 

[Chris J]

The hanging LEDs usually state what the lighting "footprint" is at certain distances from the light. Just try and match the "footprint" to your tank size. Also the reflectors change the "footprint" and lighting characteristics, ex. A 120 degree optics will cover a larger footprint but will not be as intense a 90 degree optics.