DIY LED Light Question

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SiNiStEr

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Jan 11, 2010
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Ok I know for reef tanks, if you build a DIY LED lights for it, you need to use 1w or higher LED's.

So my question is this. For FW tank what would you say what wattage you can use for a FW setup. I know the lighting requirement isn't like a SW reef tank.

If the led's you can get at like radio shack, would that be sufficient or do I need a stronger watt led thatn waht radio shack has.?

If the cost factor isn't allot, then I would love to attempt to build one for my cichlid tank that I'm slowly building.

I would appreciate all the input I can get about a DIY build like this.
 

Cory Keeper

LED Guru of Aquaria Central
Aug 7, 2007
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No, you cannot use dinky little 5mm LEDs and expect either plant growth or longevity.

I always advise the use of 3w LEDs because you get the best bang for your buck and its easier to build.

First off, what size tank. Second question, do you want plants or just to light up the tank? Third, what is your electrical knowledge and have you taken a basic electricity class?
 

XanAvaloni

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Nov 13, 2009
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Keep this discussion going, because I'd sure like to figure out a way to replace/upgrade the worthless little 9-bulb LED that came built in to this Tetra 1.5. It's a great little tank but the light is, like, feh. When you can't light up a gallon and a half of water to even "moonlight" levels you are a weak and feeble light indeed.

9v AC 200 mA is what it sez on the transformer. Plugs into the socket in the bottom of the base of the tank then wiring goes up a stem attached to same and over the top.

Hood is 1.5 x 2 in, twists 90 degrees left & right. bulbs are set in a sheet of gray plastic same as the tank trim. Not even a reflector of any kind. Bah. And nothing on it comes apart easily so some breakage is going to be required to do anything with it. Humbug.

Is there any hope for doing anything with this? or should I resign myself to it until such time as I can buy/build a better light and figure out a way to attach it? I like the idea of LED but it is a bit pricey still.
 

XanAvaloni

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Nov 13, 2009
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CWO, best pic I can find of the tank in question is in this Petco ad. A better picture than the one at Tetra's own site actually.. :)
 

DoctaQ

all your wheel are belong to us
Dec 12, 2008
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Boston
i dont think any normals leds run off of AC power and 200 ma isnt going to light up very bright.

the size of the led is not only for the intensity of lighting but also for the penetration. there are no optics that i know of for the small 5mm leds. when youre talking about the more powerful 3w+ leds they usually have some kind of focusing available that you can buy seperateley, which you need if your tank is deeper than 12-18 inches.

if youre looking to use leds to light a fish only tank, id say save your money
for plants its kinda a waste because you dont need the immense amount of light and theyre expensive to start out on.

if you insist though, read on

when are deciding on how many leds you need for a tank, you have to realize that there is no hard and fast watts per gallon rule, and especially not with leds.
for the area that an led covers (small radius, about 3 inches) the light will generally be at least equivilant to 70w of metal halide, unless it is too deep without optics(12 in)
which is more than enough for plants, id say you would have to dim them which some drivers will allow or just get weaker drivers.

you wanna put an led about every 3 inches or so, if your tank is shallow and you dont need optics, if you do, then do a little trig and figure out how much area its gonna cover with the optics that you are gonna use.

my led build costed about 250 for 18 leds
heatsink 50 bucks ( i could have cut this cost a little knowing what i know today)
drivers 60 bucks
leds 5-6 dollars each so about 90 bucks
power supply 15 bucks
other misc supplies and such was about the rest of the money

if you build your own drivers you can save a bunch but it does take some eletrical knowledge.

you also need a soldering iron and a drill press/ tapping handle and bits unless you are going with thermal adhesives.

that being said, the two leds to use are either cree xp-g ( newer, more powerful) or cree xr-e ( older but still good)

luxeon rebels can crank as much light as the xr-e but use more power, plus they will pass current through to the heatsink so you have to use some kind of insulating compound.

larger leds like the mc-e are going to spotlight the tank because each one is like ten watts and same goes for triple leds and other high power leds.
 

DoctaQ

all your wheel are belong to us
Dec 12, 2008
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Boston
CWO, best pic I can find of the tank in question is in this Petco ad. A better picture than the one at Tetra's own site actually.. :)
your best bet is to see if you can find a heatsink that you can fit inside if you gut the hood , you might need to find a way to exhaust the heat though depending on how much room. even with the heatsink you need to leave a little room for the thickness of the leds.

i just looked at the tank if its that water wonders one then you are in a pretty crappy situation.

you might try n look for a tiny heatsink and powerful fan and run a powerful led since you dont have much room to light or even place the light. it would be the first time ive seen it.
 
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