[Ron Reefman]

Originally Posted by wertoiuy

Alright, I took a look at those two, and they both look much better. I have a discount at a LFS, so do you have any recommendations from a standard vendor rather than Amazon?

Tell me what brands and the cost of the fixture your LFS carries and I'll try to help. But many/most LFS don't carry black box Chinese fixtures because they are sold do cheap on Amazon or Ebay that there is no margin for the LFS. The name brands the LFS will carry are either like the Fulval (Current Orbit or Marineland), very weak. Or considerably more expensive. Which is OK if cost isn't an objection. Brands like AI, EcoTech, Maxspect and more.

Maybe I don't understand the watts/LED argument. Say I have two equally efficient lights, each drawing 100W, one with 100 LEDs and one with 36. Why would the one with 100 LEDs perform differently than the one with 36? They supply the same watts of light, and therefore the same PAR.

You are right, you don't understand so lets try to explain it. Taking your example fixtures:

The 100w fixture with 36 leds will be much brighter and the light will penetrate much deeper into the water and even at the surface, create much more PAR. Each led is running at almost 3 watts (think 100w light bulbs).

The 100w fixture with 100 leds is running at 1 watt per led. So not nearly as bright, as powerful or as much PAR (think 10 watt nightlight bulbs). The brighter the individual bulb, the further the light will penetrate (or travel).

Think of it this way, you want to light up the driveway in front of your garage all the way out to the street with lights mounted on the garage. You get to use 1000 watts. Would you rather have ten 100 watt bulbs, or one hundred 10 watt bulbs? The light will be similar at 5 feet from the garage (maybe), but out at 20 feet or 100 feet the ten 100 watt bulbs will be far more effective than the 10 watt bulbs. Right? Does that help?

The 0.2 or even 0.5 watt leds just don't penetrate the water the same as a 3 watt led. And adding more weak 0.2 or 0.5 watt leds isn't going to make the light penetrate any deeper (they are parallel, not cumulative). The 0.5 watt led fixture is OK for a 12" deep tank. Maybe even for an 18" deep tank with easy coral. But a 3 watt led fixture will have way more PAR, 2 to 4 times as much PAR (200 vs 50) at 18" deep with 1/10th as many leds.

If that still doesn't make sense to you, say so and I'll try again. It took me a while to understand as well as I do and there is still more I could learn!