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-   -   Noob LED lighting question (http://www.plantedtank.net/forums/showthread.php?t=218993)

unicknn 01-20-2013 02:20 AM

Noob LED lighting question
 
Im in the process of planning out a planted tank. Ive had lots of tanks in the past and have always wanted to try a planted tank, I scored a free 45 gallon bow front today so its starting soon.

Im having some issues with figuring out the needed lighting.

Im planning on going for around 70 PAR( I thought I read this was medium, now its looking like this is high, can someone clarify?), this is a good start in a medium light, I want to start the tank without CO2 and then later on add it as I add more power to the lighting system... if I decide too.

Im using Hoppy's Excell and this is what Im finding:

LED spacing 2.25
PAR 70
rows 3
height 24"
cone angle 60

This shows that I can use Cree XP-E-Q5 LEDs at half power to get where Im looking to go.

My questions are this

1) the LEDs say their angles are around 125. Do I need to use LED lenses to get the desired 60 degree angle?

2) how far should the rows be spaced?

3) how long should these rows be? My tank is about 3 feet long. Im assuming that the strips should be as long as the tank.

Am I on the right track? I know Ive got alot more reading to do but these will clear up alot of confusion for me.

Thanks
Nick

moto826 01-20-2013 04:06 AM

I had LEDs on my reef tank they were ok I'm more of a halide guy my self. But do they grow plants ? What colors you use to use for good growth?

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Hoppy 01-20-2013 04:34 PM

Quote:

Originally Posted by unicknn (Post 2292297)
Im in the process of planning out a planted tank. Ive had lots of tanks in the past and have always wanted to try a planted tank, I scored a free 45 gallon bow front today so its starting soon.

Im having some issues with figuring out the needed lighting.

Im planning on going for around 70 PAR( I thought I read this was medium, now its looking like this is high, can someone clarify?),

In my opinion you should treat 70 PAR as high light, so good CO2 is essential.
Quote:

this is a good start in a medium light, I want to start the tank without CO2 and then later on add it as I add more power to the lighting system... if I decide too.

Im using Hoppy's Excell and this is what Im finding:

LED spacing 2.25
PAR 70
rows 3
height 24"
cone angle 60

This shows that I can use Cree XP-E-Q5 LEDs at half power to get where Im looking to go.

My questions are this

1) the LEDs say their angles are around 125. Do I need to use LED lenses to get the desired 60 degree angle?
Yes, you do need 60 degree optics to get the 60 degree beam angle.
Quote:


2) how far should the rows be spaced?
The row spacing should be about the same as the LED spacing, so 2-3 inches should work fine.
Quote:


3) how long should these rows be? My tank is about 3 feet long. Im assuming that the strips should be as long as the tank.
If the rows are as long as the tank you get a lot of light spilled over the ends of the tank. If you make the rows much shorter, the PAR drops quite at bit at the ends of the tank, even though reflected light off the end glass does increase the PAR some. You can make the rows be almost as much shorter than the tank as the space from the rows to the front and back glass, or just make the rows about 2 LEDs short on each end.
Quote:


Am I on the right track? I know Ive got alot more reading to do but these will clear up alot of confusion for me.

Thanks
Nick
I think you are on the right track, but be sure to use a dimmable LED driver, because that calculator can't be assumed to give an exact prediction of PAR, and, for the same reason, design based on the maximum PAR you think you might want.

unicknn 01-20-2013 05:01 PM

so basically if I use a dimmable driver then I can build this one for high light and then just dim it down to medium? I actually just looked up the cost of the LEDs and was shocked at the price. I may end up going with a florescent light. Im gonna keep reading though. I want to do this but I want to do it right.

Hoppy 01-21-2013 03:36 AM

Yes, considering your investment in a DIY light, you don't want to end up with too little light and no easy way to increase it. So, you design for more light than you want, and use a dimmable driver so you can reduce the intensity, if necessary. Today the cheaper option for many tank sizes would be manufactured LED lights, like the Finnex ones.


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