actualy I bought two yesterday at home depot. 60 watt equiv, dimable 19.00 each, and I am very impressed with them. I tried dimmable CFLs but they suck and dim at different rates so I took them back.

house hold LEDs are dropping in price quite quickly now that there is more compatition. but the bigger thing we should worry about here is the mercury in CFLs. I am slowly changing out all my cfl's to LED now that there are good options in a reasonable price now.

Steve

You divide cubic inches by 231 to get gallons not 324. But I agree that might not be the best way to decide on the amount of LEDs, kind of similar to the 5W per gallon deal.

As far as I know you need to be in the range of one LED for each 10-15 square inches. So for example take your tank foot print to be 48"x24", that's 1152sq" meaning you'll want to aim for a range within 76 to 115 LEDs, give or take. Now deciding on a final number will depend on your tank height and coral requirements. For something average say 24" tall and mixed reef with SPS you'd probably aim right in the middle of that range.

That's nice but personally don't really believe it as HD didn't have much at all for 60W equivalents last time I checked, the ones they did have where $40+ and IMO still dimmer than the CF 60W equivalent. However that is my personal opinion but I still would like to see a link to the 60W for $19 cause maybe I missed something last time. Still $19 for one light bulb is a decent amount, really it's not going to save you money.

For the price difference, I'll take a chance with mercury poisoning:loco:

I would disagree with that completely. As the guy with the 2 1/2 foot tall tank needs way more LEDs per square inch than a 6 inch deep nano tank.

You calculate what heatsinks you need based on the surface area but LED density is most definitely determined by volume.

Correct I wasn't finding the gallons. We came up with the 324 figure based on some test tanks I have here to calculate an approximate recommended 3W LEDs per tank size. That formula would give you 86 LEDs for that tank size you mentioned. You are right though you then use that number and go up or down based on what your light requirements are.

haha thats right ... dislexia is wonderfull, guess I should finnish my coffee before I start reading

Steve

actualy no.. the spacing of your LEDs depends on the lense your going to use on it. so in a very round about way yes the depth of the tank and your PAR requirments at the depth will determin the lense. then the combanation of the lense you use and the hight of the fixture above the surfface to give you even blending of the blue and white will give you the spacing of the LEDs. then the physical surface area will give you how many you need to use at that spacing.

now as for heat sinks, nothing to do with the surface area, but rather with the amount of watts dispersed per square inch. using a 3 watt LED on a star you want a heat sink that will disperce a min of 3watt / sq in I see most are up around the 6watt/sq in, and you can use air movment to increase this value.

if I use your fourmula it tells me I need 20 LEDs for my 30 gal tank, where from mapping my tank and projecting PAR values I know I need 36 to 48 LEDs (calculation was actualy 42) I can get away with 36 but might go 48 as I can get a kit with that number already. so your formula would have probably been find in my tank with no optics and low to med light corals, but not for a pure SPS tank with high light corals at all levels in the tank.

so I guess if it is bassed of one optic choice and now requirement for a specific par level at the bottom of the tank it would work..

Steve

yes

The degree of optics also impact the coverage significantly.

Also, you can save on LEDs depending on where you place your coral. If you keep all your sps in the middle, you dont need a large density of LEDs at the ends of the tank.

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Cree Leds are all over the map now for lumens. Some are 106, some are 230, some are 350. All are considered "3 watt". You can save money and get 3-ups. which I would cosider as 1 Led. So really, the amount you need depends entirely on the emitter you are using.

are there more pictures, I sea lot of text