How many LEDs

[fishguy95]

I am doing a project for science fair this year and am going to put a few frags in my DT under halides and have the same kind of frags in my refugium under LEDs. I have good flow in my refugium and it is a completly full 30 gallon tank. I was thinking about getting the 12 LED kit with dimable driver and then later getting 2 more of the kits so that I can have 36 LEDs total over my 55 gallon display tank. My question is, will 12 LEDs be enough light for the 30 gallon refugium I will have the corals right under the LEDs. I intend on testing for atleast 7-8 months. Thanks for the help. Landon

 

[fishguy95]

The LED kit will come from rapidLed.

 

[fishguy95]

Can any one plz help.

 

[Tecnomage]

What are the dimensions of the 30 gallon? I'm thinking you might need more like 18-24. How high will the lights be off the water surface? You can email rapidled and usually get a response back in a couple hours.

 

[fishguy95]

It is 12 FtB x 30 EtE x 19 TtB. The lights would only be about 4 in. from the water, I was only going to cover half the tank for the test. I will later use this fixture over my 55 gallon Dt along with 2 more of the same 12 bulb fixtures. I only wanted to use it on the 30 gallon for about 7 months. I will have the frags supported by frag racks so that I can keep them close to the light.

 

[Tecnomage]

Ok, that makes more sense, sorry I was reading on my phone. If you're only going cover half the tank I think you'd be fine with 12 LED kit. You can choose optics in the kit in preparation for the 55G, how high would the lights be off your 55G? For the test you probably wouldn't want to use optics.

 

[fishguy95]

My halides are currently 18in above the water but I will build a new canopy for the LEDs. I was thinking 12in would be how high I will have them so that I can use 40 degree optics.

 

[Guerry]

if you don't have par meter be very careful not to bleach all of your corals, LEDs produce much higher par than MH lighting when I changed from MH lighing to LEDs over my 209gal DT I bought an Apogee 200 and it saved me a ton of money! had I not done the par testing during the switch I would have cooked all my corals. I had 400watt MH lighting which I thought it would of had stronger par LOL they were producing 200par at 12" below water suface I now have 500par at same depth which I brought to these levels over months not days and LEDs are only running at 50%. Almost forgot I have 144 3watt Cree emitters with Carlco wide optics

 

[BryNik]

Surprised no one has asked: what kind of frags? I use a 20g long for my sump and I use (2) 15000K (advertised as 20000k but closer to 15000k) 10w leds over mine with 60* optics. The LEDs were sourced from eBay and they run at 32vdc off a computer monitor power supply I had lying around. It's been going for almost a year like this. Growing coralline like mad and I don't doubt it'd do LPS with no problem. If I added two more, I have no doubt it would grow SPS. Total cost of the fixture ~$25. Price doesn't include the piece of scrap aluminum I used for the heatsink or the dime-a-dozen power supply. If this is an experiment on a budget; I'd heavily suggest going with those LEDs. They're Chinese, but I've run them overvolted with a crappy heatsink and not lost a single diode. My two cents.
[h=1]search: LED Lamp Bulb Light 800LM 10W for Aquarium Fish Tank[/h]-Hope this helps

 

[fishguy95]

Thanks, I was planning on using zoas and birdsnest.

 

[BryNik]

Keep me posted! I'd love to do a long term comparo like this, but the fact is: I'm too lazy! I wish more folks did this to prove the technology. Glad you're taking initiative.

 

[BryNik]

One thing, if you use those leds wide open, they get HOT. They are the hottest running leds I've used. A nice big heatsink with a fan is mandatory. Doesn't have to be fancy, just a thick chunk of aluminum and a fan. A good, simple, cheap heatsink is a piece of thick wall square aluminum tubing with a square computer fan in one end.

 

[BryNik]

something like this with a fan jammed in the end: ALUMINUM SQUARE TUBING 3" x 3" x .250 (1/4") x 12" | eBay screw, rivet or silicone thermal glue your LEDS on, wire it and you're done.

 

[fishguy95]

I was considering buying a heat sink from the site and then have cold water running through some tubing to a mini fridge that I am useing as a chiller right now, I hope to upgrade to a real chiller soon for consitancy but, the mini fridge is working right now.

 

[BryNik]

It's a great method of moving heat. Liquid moves a lot more heat than air and you can use a much smaller heat sink. I did that for a while and used 1" square thin wall aluminum tubing and 3/8" nylon hose. The downside to that is; all the complexity, power and heat you're getting rid of by going LED gets nullified by running an extra pump and refrigerator. The pump uses power and makes heat. The fridge uses a LOT of power and makes more heat than it removes (in the aquarium room). If you're getting rid of equivalent halides for the LED conversion, your heat in the aquarium room goes way down, making air cooling more efficient. I'm currently not using a fan on my 2 10watt sump lights. Just a chunk of 4x4x1/8" aluminum angle. The heat is soaked by the angle and radiated up (since heat rises...) into the floor of my DT. The diodes get hot, but I'm really not worried about a couple $10 diodes lasting 50,000 hours. I run my sump lights on a mostly reverse schedule to my DT, so they take some load off the heater for the DT when it's cool at night, not appreciably but some.

A piece of square aluminum tubing (exhaust ducted away from your aquarium setup) with a fan would definitely cool the LEDs plenty and keep the heat away from your DT if you're concerned about that. If you're struggling with keeping your DT temps down, remember that a fridge or chiller has to exchange the heat somewhere and if it's in the same room as the DT, that hot air is right back where it started without proper air circulation.

Anyways, the cool thing about LEDs is simplicity and efficiency. Overengineering sort of defeats the purpose.