Interested in knowing my PAR

[eamike261]

Hey I recently switched from 2x T5 bulbs to a 24x LED build over my 20 gallon tank and I'd really like to know the PAR values around my tank. I'd rather not buy a PAR meter for a one time use but I think I've seen some friendly people on the forums who are willing to come over and do it for a small price.

Is this something that anyone would be willing to do? I don't know whats fair to offer. Can anyone chime on on this?

I live in East Amherst btw.

 

[teamdulski]

If they are 3w Crees...A LOT. I have 24 (constant current) over my 34 gal display and it's way too much.

 

[eamike261]

Well thats 1 of the biggest reasons I want to know. They are Cree but we did a dimmable circuit so it can range from something like 200mA to 900mA, I believe the constant currents are 700mA. But I'm curious how the PAR changes with that range of strength.

 

[bassplaya12]

I would also like to know the par values

 

[der_wille_zur_macht]

Keep in mind that it's not really effective to compare PAR measured on an LED tank with PAR measured with other forms of lighting. The typical hobbyist-grade PAR meters don't have a perfectly flat response curve, so they tend to "under report" PAR on typical LED rigs. There have been a couple good threads on this across the forums in the last few months but I am struggling to find them now.

The good news about LEDs is that there's lots of documentation on them from the manufacturers (compared to, say, MH lamps used in the hobby) so once you have a good idea of PAR on a few fixtures, you can do some math and come pretty close to guessing the PAR on other fixtures. If you post your exact specs here (LED count, model, bin, optics, drive current, spacing, height above the tank) we can take turns guessing.

 

[eamike261]

Hmm I didn't realize the type of light changed how the PAR was read. I thought that was sort of the 1 thing that actually didn't change across different forms of lighting. Oh well, I've tried to something similar to what you said, about guessing the PAR, but I have no clue how accurate I've been. All I know is that its plenty of light haha.

But the exact specs:
12x 3w Cree Royal Blue LEDs
11x 3w Cree Cool White LEDs
1x 3w Phillips Red LED
23x 80 degree optics (not on the red LED)

The maximum current for our dimmer is 900mA but keep the blues at maybe 600-700mA and the whites at 500-600mA.

the heat sink looks like this: (each X is an LED)
|------------20"-----------|

|--------------------------|
|......X.........X..........X......|
|..X..X..X..X..X..X..X..X..X..|
|..X..X..X..X..X..X..X..X..X..|
|......X.........X..........X......|
|--------------------------|

The tank is a standard 20 gallon.
24" wide by 13" deep by 17" high

The light is 9" above the water.

 

[SkiFletch]

You mention the color temp of your lamps but what model LED's? XR-E? XP-G? etc

 

[bassplaya12]

You mention the color temp of your lamps but what model LED's? XR-E? XP-G? etc

white's are xp-g, blues should be xp-e