(Another) DIY LED Build - Linear Design
- Thread starter katchupoy
- Start date
S2minute
New member
LEDs
LEDs
Well, if we are trying to achive 500 par at the water surface and 100 at the sandbed...then those par readings even with 2 leds overlapping....are not nearly enough...right? I mean 30 par at the surface...that sounds way off what we want.
LEDs
What if we measure 2 LEDs...
2 LEDs 3.5 inches apart... here are the readings...
Well its not twice as expected... but its still linear...
The two lower curves represents two LEDs and see where the two intersects? that is 178/2 par readings..
Well, if we are trying to achive 500 par at the water surface and 100 at the sandbed...then those par readings even with 2 leds overlapping....are not nearly enough...right? I mean 30 par at the surface...that sounds way off what we want.
TheFishMan65
New member
Yes, but that is a 2 dimensional picture. Add 2 more LEDs since it is a row and each will contribute about 30 (times 2) so now the total is about 238. And then we have two in the front and two in the back so add another 160 (40 from each) - 368. We are getting there. Now what was the current on these?
Also I am not sure we need 500. I bleached a monti cap (several actually), a birdnest, and one other IIRC with 300 on the surface and the coral about 6 inches down. I also bleached a monti cap about 18 inches down. Now, it could be something else since I am just starting on some corals.
Also I am not sure we need 500. I bleached a monti cap (several actually), a birdnest, and one other IIRC with 300 on the surface and the coral about 6 inches down. I also bleached a monti cap about 18 inches down. Now, it could be something else since I am just starting on some corals.
TheFishMan65
New member
Those would work (little less efficient) the math is will just odd
Current = Voltage / 1.2 ohms
Try looking for some 1/2 - 1 watt 0.1 ohm then you can just multiply by ten.
Where did you look?
Current = Voltage / 1.2 ohms
Try looking for some 1/2 - 1 watt 0.1 ohm then you can just multiply by ten.
Where did you look?
TheFishMan65
New member
I am assuming the #10 means you need 10. Yes 1 watt 0.1 ohm. At 1 amp this will have
watts (heat) = 1 amp * 1 amp * 0.1 ahms or 0.1 watts.
So you could use a 1/10 watt resistor, but it would get very hot and be more likely to fail. You could probably use any wattage over 0.5 watts for a 0.1 ohm resistor.
watts (heat) = 1 amp * 1 amp * 0.1 ahms or 0.1 watts.
So you could use a 1/10 watt resistor, but it would get very hot and be more likely to fail. You could probably use any wattage over 0.5 watts for a 0.1 ohm resistor.
katchupoy
New member
Haha, I stopped posting because i thought everybody unsubscribed already and thinking of creating another thread just for the PAR reading... my mistake.
Fishman is correct. This is purely 2 dimensional and just wanting to prove here if the you can actually predict how many PAR you are going to have at any given number of LEDs if you know how much PAR per LED or group of LEDs.
I will continue posting then if this is of interest to everybody...
oceanreefs
New member
Katcupoy I did sent you pm
S2minute
New member
leds
leds
Fishman, your alittle fimular with the setup i`m working on,(56 leds per 2`x2` sq feet approx. 7 of which are XM-Ls. This is about 9.6 sq inches per led. This is high end BUT you really think that will put out more par than someone running a 400w MH over the same area? Let alone other supp lighting they may add to it?
leds
Fishman, your alittle fimular with the setup i`m working on,(56 leds per 2`x2` sq feet approx. 7 of which are XM-Ls. This is about 9.6 sq inches per led. This is high end BUT you really think that will put out more par than someone running a 400w MH over the same area? Let alone other supp lighting they may add to it?
TheFishMan65
New member
I have 24 LED for a 24x18 area. I bleached the SPS with 50/50 XR-Es. Now I admit I don't have a lot of experience with SPS, but they looked OK (to me) with T8 before I switched over (but I also added bio pellets about the same time). So it could be a water quality issue). I have also read numerous places that about 72 watts of LEDs is the same as 250 MH (this included one that was 72 1 watt LEDs). So I think you can reach the output of a 600 MH.
BUT
How do you measure the output. I had 300 PAR at the surface (I know I need to measure the bottom, but someone had me buying LEDs for them) where as with a MH I have read some where online that 500 is the range for the surface (sorry no experience with MH). I know that blue is under reported with PAR meters. But how much more blue are LEDs than MH folks say they look the same, but LED blue is ideal (from what I have read) for coral growth where as the MH has blue in the not so ideal range. Buy low sell high - oh wait start low and turn them up as needed
Does that help?
BUT
How do you measure the output. I had 300 PAR at the surface (I know I need to measure the bottom, but someone had me buying LEDs for them) where as with a MH I have read some where online that 500 is the range for the surface (sorry no experience with MH). I know that blue is under reported with PAR meters. But how much more blue are LEDs than MH folks say they look the same, but LED blue is ideal (from what I have read) for coral growth where as the MH has blue in the not so ideal range. Buy low sell high - oh wait start low and turn them up as needed
Does that help?
TheFishMan65
New member
katchup do/can surface plots in excel? At least that is what I think we need. It would be inches in the X and Y and then the color would tell how much PAR in a given area. Do you know what I am talking about?
Gillguy
New member
Katchupoy, I have a 90 gal 48 x 18 x 24 tank with a 3" middle bracket. I purchased 36 3w leds with 60 degree optics. I have 2 heatsinks that are 12" x 4". I plan on putting 18 leds on each heatsink. 2 outside rows of 7 leds and a center row with 4. The heatsinks will be in the center of the canopy with 2 T5 lamps on each side. In other words, 4 T5 x 54 watt total with 36 3watt leds down the middle. The leds and T5 will be 13" off the water. The main question I need is do you think the heatsinks are long enough for coverage throughout the tank. What if I use 80 degree optics? I ask because in the future I might remove the T5 and go all leds.
TheFishMan65
New member
That heat sink seems a little small to me. You will have less than 2 inches between your LEDs.
I would use at least 80 and maybe 60s.
I would use at least 80 and maybe 60s.
Gillguy
New member
What if I use 8 x 80 degree lenses on the edges of the heatsinks and 60's in the middle? Would that give me coverage at the edges of the tank and under the middle bracket of the tank? Also, would I need fans directly on top of the heatsinks? I already have two fans blowing accross the T5's and out the back of the canopy. Thanks
TheFishMan65
New member
It might cover, but what do you want to keep?
Depends on how hard you drive the LEDs at one amp or more I would say yes.
Depends on how hard you drive the LEDs at one amp or more I would say yes.
