What par reading am i looking for?

[TaznTee]

Hi,

Our 75g tank has had LEDs for a month or so now. Tank is less than a year old, and we are supporting LPS/SPS frags right now as we learn.

Worried about burning them, and am orderring a par meter. I keep hearing that readingd are different for leds, but can't find what my readjngs should be.

What should I be aiming for par level wise? Mid, and at the bottom...tank is 24 in deep. And obviously there must be limits on how long the highest levels should be, etc.

Am I missing some key website or article with this info?

Thanks so much

[sirreal63]

This is a pretty decent chart to help. It is not perfect but is a good starting point.

http://img.photobucket.com/albums/v362/sirreal63/IMG_0421.jpg

[Ron Reefman]

+1
Jack's numbers are a real good starting point.
If you can get 150-250 at the bottom of a 24" deep tank, you're in pretty good shape. Some of the ranges in the chart are a lot narrower than they need to be. I have ricordea (a soft coral) near the top of my tank just out from under the leds and they get a PAR of 500 and are growing like weeds!

[t4zalews]

I'd recommend the 150-300 range as well....I was running 2 radiums and my par was 400 on the sandbed and 600+ in the middle of the tank and I never had good coral coloration.

http://www.vividaquariums.com/aquariumLightExperiment.asp

Look at these PAR numbers from Vivid's 800 tank. They have some of the best coral coloration I have seen.

Obviously higher PAR's work but I would strongly suggested SLOWLY acclimating them to such higher PAR levels.

[TaznTee]

thanks so much - that grid is helpful, I have a monti and a birdsnest frag so want to make sure I do this right from the get-go.

These are the PAR levels at the peak right, that they only get a few hours/day?

[dzhuo]

Jack,
Where did you get these numbers and who post them?

(Sorry for the curt message. Sent from phone)

[sirreal63]

It was a chart from MACNA 2010, I believe, and I am not sure who originally posted it. I saved the image because the question comes up so frequently and though I don't think it is perfect, it is a very good starting point for PAR levels. Unfortunately there is no set in stone PAR levels, as you know, it can vary tremendously from tank to tank and there are a lot of factors that come into play. But for a general chart, it is pretty good.

[dzhuo]

Do you remember what these numbers mean? For example, are the upper limit saturation or photoinhibition point? What about the lower number? To trigger photosynthesis?

Unfortunately there is no set in stone PAR levels, as you know, it can vary tremendously from tank to tank and there are a lot of factors that come into play.

I think you are absolutely right although if we try to compare those find in the corals' natural inhabit, there are more reference data collected by Danna:

Feature Article: How Much Light?! Analyses of Selected Shallow Water Invertebrates' Light Requirements (http://www.advancedaquarist.com/2007/3/aafeature1)

Have you seen these data before?

[MikeTR]

I'd recommend the 150-300 range as well....I was running 2 radiums and my par was 400 on the sandbed and 600+ in the middle of the tank and I never had good coral coloration.

http://www.vividaquariums.com/aquariumLightExperiment.asp

Look at these PAR numbers from Vivid's 800 tank. They have some of the best coral coloration I have seen.

Obviously higher PAR's work but I would strongly suggested SLOWLY acclimating them to such higher PAR levels.

Same experience and par with the radiums. Switched to 150w phoenix and have never looked back. Still getting 200 par on the sandbed and growing everything from zoas to sps.

[sirreal63]

Yes I have and it is a great article. PAR levels change based on a variety of factors. Water clarity is one area that is often overlooked, but it is why I can bleach sps under 150 watt fixtures and others won't under much higher wattage lights. It also is a partial explanation to how I get such high PAR numbers with the 150's.

I think his later article is probably even better.
http://www.advancedaquarist.com/2012/12/corals