treelimbjim, that other post was done back when I was still trying to make sense out of designing a LED light. I wouldn't recommend following that method now. The calculator is based on more data and more varied data. If you have taken some PAR measurements with other configurations I would appreciate receiving the data so I can see how it fits in with the other data I have.
This is still an evolving design process, but I haven't seen a better process.
Trying to answer "How many (and type) LEDs to use my 70 gal?" or simply, "Is 24 XPG enough? 36?"
I've been estimating with spreadsheet V.3.
Tank: 48wx18dx20h, 3" substrate
Frame: 1.5" aluminum extrusions, 3 x 48" rails on 5.25" centers.
Table for PAR est. for L,M,H light (see below)
LED height: Tank_height + LED_Height_above_water - Substrate_depth
Conditional format: 1) PAR background is blue, green, orange for L,M,H light. 2) current background is red when >rating.
Table for Spread with LED_Height and Cone_Angle
I'm not clear about how the "rows" work. I'm trying the geometric mean of LED_spacing and my LED_row_spacing.
Trying to validate the calculations, I ran across 84212-designing-building-led-fixture-22.html#post1102937
... and the spreadsheet isn't coming close to real world observations.
The number and spacing of LEDs for any size tank can be calculated with reasonable accuracy using a Excel Spreadsheet "calculator" shown here: http://www.plantedtank.net/forums/di...ml#post1803323 I doubt that you will want to use Cree XP-G LEDs for that small a tank. Perhaps XR-E would be a better choice.
I understand you are the aquarium lighting mentor. I was sent over here from Nano Reef by Evilc66. I am looking for some help with the lighting for my Aquarium.
I am new to the aquarium/lighting arena. I have a Fluval 12 gallon tank with fresh water. I am wanting to grow some high light plants and carpet plants.
I am considering a DIY modification to the lighting. I am looking into getting the CREE XP-G LED's. What do you think is the appropriate amount of cool white led's and the total amount of watts/lumens for the 12 gallon?
Surprisingly everything has been fine. I am running pressurized CO2 in the 29g now, and the plants are growing crazy. The issue is I am starting to see some GSA. I have had these lights on the tank for two months now. I'll try putting a layer of window screen on and see if that helps the algae issue. The lights are on right now for 8.5 hrs a day.
Two T5HO bulbs close together, with a good reflector, should give you high light at the substrate (24 inches away, assuming 3 inches of substrate.) That is too much light for what you are trying to do. A layer of figerglass window screen would reduce that to medium light, which may still be a bit more light than you need. Two layers reduce it to low light, just about right. I'm assuming the lights are both T5HO, and that they overlap in the middle, by two feet. That two feet of overlap is even higher light.
I suggest you try for only low light, not use CO2, and if you are concerned about keeping enough oxygen in the water, direct filter returns up towards the water surface to create surface rippling across the whole length of the tank.