thats kinda my thing too im using my 250w halide on my 20g and can upgrade to a larger tank with no upgrade to light as it has a good refector if i were to order leds for my 20g and wanted to upgrade back to my 60g cube is the spread gonna cover the extra width??:)

they are insanely bright lol but the beauty is you can power them down which leads to my next question if you have to power them down what are you really losing??

The spread is all about the optics. Most LEDs come with 125 degree lens on them. Most users of tanks that big put something like 60 degree optics on the LEDs to focus the light on the area. To get an output of a 250W MH you can do about 36 XP series LEDs or 28 XP/XM mix. I would think coverage is more of an issue of a single point light than a bunch of smaller spread out LEDs. For instance my penisula casts shadows because of how my rock work, under a standard MH fixture. With LEDs, you can spread them out with the correct optics and you can get more coverage, or tighten them up and do spotlight effects.

Here is some info on picking the right optic but it will give you an idea how the coverage works depending on which optics you choose and how high you hang the light. http://www.ledgroupbuy.com/pages/Cho...ght-optic.html

Only thing you are loosing is intensity I guess? Not sure what the question is.

i guess you answered it lol so if i were to power them down what the benefit of having them full power say to half power?? or vice versa what would the effect be say to corals what would they lose or gain??

Less power
Cons: Less lm, so less light for the corals
Pros: LEDs run at lower heat so they last longer and they are easier to cool

More Power
Cons: LEDs run hotter, harder to cool, can reduce the life of the LED if they are running hot for too long
Pros: More light for your corals


Someone posted a very interesting picture somewhere which I should have saved on dimming his LED fixture when he had just put in the sand into his aquarium. The sand "grabbed" the light and it was interesting to see how dimming effected the intensity.

The only way I can explain it is if you had a balloon and you filled it with air and put it inside an empty tank. The area of the balloon was the most intense part of the light (100 intensity). A bit outside the area it fades down to 0.

So as you release air out of the balloon you can imagine it getting smaller and the intense part of the light becomes smaller. This is you running them at lower power. Now you add air to the balloon, the intense part of the light gets bigger and it starts getting closer to the sand and hitting the glass. This is you turning up the power.

Its not efficient to turn up the power to hit the sand, its more efficient to just add optics to control the light to where you want it to go.

im kicking my self for not saving that image. I might have to just grab a tank and throw some sand in it and an LED light over it and dim it to show you what i mean. It was kinda eye opening.

Maybe I should start a new thread for questions/answers on LEDs for everyone on canreef. Interested?

id be for sure do it up:) theres alot of people who have questions including my self:)

I just set two of these 100w led spotlights over a 220G 2 months ago, with dimable ballasts.

http://www.ecoxotic.com/catalog/prod.../89/image/393/

http://www.ecoxotic.com/aquarium-led...-pendants.html


-easily spreads the tank
-12" above the water and may be too bright (testing stage, currently dimmed to 75%)
-costs about $250 more then what I would have spend on MH
-way less heat transfer
-brings out corals colours better then any light I have seen

cannot comment on coral growth as of yet with these

Nothing wrong with MH, but so far these are proving to be better IMO.

Ryan, with spots like that, depending on color, I could see these replacing MH. As long as growth is good long term. Keep us posted.