Join Date: Jul 2010
Location: Outside Philadelphia, PA
When you get into tanks 72 inches long that are 24 inches deep you likely have a tank that is 18 or 24 inches wide. This is a lot of area to cover. You will also likely have a center brace on the tank.
With LED your going to have two general options. Use strip lighting, similar to what you have, or go with pendant lighting. If you have a center brace, you go with 4 to 6, 36 inch strip lights. If you go with pendants, you go with 2, 3 or 4 pendants. I don't recommend 3 if the tank has a center brace.
Now you have additional considerations. LED lighting likes to go straight down. Depending on the arrangement of everything, this can leave you with dark corners or ends in the tank, and dark areas near the surface. This is on thing I don't like at all, and why I like multiple fixtures for the tank. Generally, I think you get better results with more, but lessor wattage fixtures. This can have a cost problem because two smaller wattage fixtures can often cost a lot more than one large wattage fixture.
You might be able to find lighting that will span a 6 foot tank, or build a canopy to do this, but I find this solution to be really awkward for working on the tank. Think about needing to remove it for major work. (grin)
Now it gets really tricky. There are a lot of good LED fixtures available both in pendants and strip lights. You need to make your selection based upon your budget, and what you want out of the lighting. You are also going to see lots of recommendations, mostly people recommending the fixture they bought. While I'm sure they love their lighting, for a lot of them, it's only the first or second LED lighting they ever bought, so they are not often objective.
At this point, I can tell you that I use two Current USA Satellite LED + PRO fixtures on my 90 gal (4 feet long) planted tank. I like the light I get, but I find the set up of the controller to be a real pain, and somewhat limited in function. If I were using them on a 6 foot tank, I'd use 4, 36 inch fixtures. This would have a downside. You would need to set up each fixture individually. If I were doinf this again, and money was no object, I think I'd go with EcoTech pendants or Kessil pendants. They would cost lots more, but they can be connected together and controlled from a single point.
Lastly, you can use the LED lighting made for reef systems, if you can dial back the blues, but this is a very expensive solution, and your paying for a lot of blue light you will not use. Shop carefully.