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Mortis 12-06-2012 12:59 PM

Help building a LED fixture
Hey guys so I have found someone who will be able to make me an LED fixture that I will use above my main display tank that is 30x18x16 inches lxbxh. It will be a dimmable fixture which I think is important in an LED setup. The fixture will be using 3W Cree XPGs. I know all my questions are inter related but Ive broken it down to help me understand better :

1] How many Watts do I need for a Med to High (dimmable) light tank ? Right now I am thinking 18 LEDs for a total of 54W

2] Placement : Im thinking 3 rows of 6 each

3] Optics : Is 90 degrees good for planted tanks with regards to spread and penetration ?

4] Should the fixture be about the same or quite a bit smaller than the tank size ? Considering the spread with the optics and such that all corners of the tank should be lit and the highest that the fixture can be above the surface is 10inches.

Thanks !

Hoppy 12-06-2012 03:00 PM

See if this helps:

Mortis 12-06-2012 03:46 PM

Thanks for the link Hoppy but I nearly had a heart attack seeing the maths involved :O

I will switch to 60 degree optics. I am considering 21 or 24 LEDs also instead since I will be able to dim them anyway. Anyy suggestions on if it will be overkill ?

Ideally I am currently and plan on continuing to run my tank at medium light but would like the flexibility to go from high to low and Im guessing this functionality would be provided by the dimmable driver. Im just wondering how many LEDs would suit this for my size tank.

Could you help me out with the calculations in the link you provided Hoppy ?

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