PAR for LED SPS tank

[brad]

I want to add Acropora to my tank, and I have a PAR meter, but I know it under-weights LED lights. Is the best way to measure how much light I need by PAR, wattage, total number of LEDs, etc? I just got done building a custom LED hood, my total wattage ended up less than I planned, so I want to add more light.

 

[Reef Bass]

I attended a lecture by Dana Riddle, a coral researcher with the scientific equipment to objectively measure his findings, on the influences of light on coral pigments. When asked essentially this question, he responded that the reading provided, while not exact, was suffcient as a low end ballpark.

 

[gbru316]

With an apogee meter, your royal blues will read about 25-30% low. No other calculations should really be necessary.

Anything shorter than royal blue (in wavelength) will read lower, but usually these wavelengths are just used for supplementation.

 

[brad]

your royal blues will read about 25-30% low

So if I really have 100 PAR of royal blues, do you mean that will be measured as 25-30 PAR? Or 70 -75 PAR?

I've seen a lot of articles, some say 200 PAR is too much and will cause shutdown, others say 1200 PAR gives good results.

 

[gbru316]

So if I really have 100 PAR of royal blues, do you mean that will be measured as 25-30 PAR? Or 70 -75 PAR?

I've seen a lot of articles, some say 200 PAR is too much and will cause shutdown, others say 1200 PAR gives good results.

If the meter is measuring 100, in reality it's 125-130.

I've found that spectrum plays a rather large role in the amount of PAR a coral can handle. It's rather impossible to give concrete numbers regarding adequate PAR as it's hardly the sole variable.


That being said, if you only have royal blue and white LED's, I'd stick to the lower end of the PAR recommendations. If you have other colors thrown in (true violet, cyan, deep red, cool blue, etc), It wouldn't hurt to shoot for higher numbers.

It's all a guessing game, try something, observe the response then adjust fire and repeat.

 

[brad]

Guessing Acropora should be between 150-350 measured PAR.

 

[gbru316]

Guessing Acropora should be between 150-350 measured PAR.

sure. Then consider species that may be out of water at some point during the tides are exposed to 2000+ during the summer months :spin1:

 

[jerpa]

The Apogee meter under reads light at 450nm by 20%. White LED's should be read fairly accurately so only add 20% to the par readings from your blue LED's. It also reads red wavelengths about 20% higher than they actually are so keep that in mind if you include red LED's. If you are using a "full spectrum" LED setup I have found this to be a moot point. Switching from MH to various LED's and back to MH again I have found corals respond to the same levels of PAR regardless of the source. If you are using straight RB/CW I would do the math, especially if the build has a much larger ratio of blues to whites.

 

[brad]

I am switching from metal halides, but also switching from non-SPS to SPS. I did the math, and had both higher wattage and higher PAR than what I ended up with after doing the soldering, so now I need to add more LEDs.

I don't like red light.

 

[Nano sapiens]

Guessing Acropora should be between 150-350 measured PAR.

Depends on the species. It's safe to say that most Acros we keep prefer brighter light, but certainly not all.

I have a few Acros that do well under mostly full spectrum LEDs at 130-180 PAR. They are species that are known as 'mid to lower light', but some can take higher light, too.