PAR - What Does It Mean?

[kingfisherfleshy]

Im aware of what PAR physically is...but in reading some threads, Im not sure what PAR means CORAL wise.

Can we maybe get a sticky talking about PAR and what you would look for to grow certain kinds of corals? I think thats the main point of knowing your lighting and I cant seem to find any information on what PAR values equate to stocking wise.

Thanks

 

[Aloha Corals]

Photosynthetically active radiation

Photosynthetically active radiation - Wikipedia, the free encyclopedia

 

[kingfisherfleshy]

Mahalo...but...that isnt what I am asking.

When you see PAR readings, what does that mean? What sort of PAR readings do you want to have good growth and color on SPS, LPS, sofites ECT?

 

[CookieJar]

that's a complicated answer, it's not just PAR for coral growth, PAR is 1 factor. To give you a ballpark, at the bottom of a tank a common PAR is 100-150, middle 250 and top around 400. PAR varies quite a bit depending on light source location relative to PAR measurement, water surface, etc. you might want to check out Melev's reef where he did a good analysis of PAR using different bulbs & reflectors.

 

[kingfisherfleshy]

Thats better...but there isnt a certain par value someone can give me?

"I need X PAR to grow acros in my tank."

What is X?

I hear all this talk about the numbers...but it just seems like all relative comparisons without knowing what that means to the corals.

 

[Troylee]

Depends on the acro or monti... They will survive in 100 par but thrive in 1000 par... Depending on the coral etc... It's more of a observation thing than any IME

 

[kingfisherfleshy]

Ha ha this is disappointing seeing as how I was hoping for something that would resolve a "What sort of lights do I use" question. Oh well...thanks for trying guys.

 

[Aloha Corals]

Ha ha this is disappointing seeing as how I was hoping for something that would resolve a "What sort of lights do I use" question. Oh well...thanks for trying guys.

This hobby is tough, there is no set standard for anything. Some things work for some and not for others.

There is a lot more variables in coral growth than just PAR. Most tanks will never come close to the par readings of the ocean. Shallow reefs in the wild can see upwards of 2500 PAR. Though i have seen good growth in the same coral (my zoas) in as little as 200-500 PAR.

k3v

 

[kingfisherfleshy]

Yea, if one thing is true that I have learned in the last nine years of reefing its exactly that. Nothing works for everyone. I was just wondering what people are shooting for.

Im considering a fixture, but if it only gets 925 at the surface, that doesnt leave me much room for error, (or corals) before I have to start going to less demanding things.

Figuring an upgrade to LED might as well come at a time when I would have to replace my MH bulbs anyways, so this is why I am looking into it.

 

[nayrgaijin]

I think you're asking a very broad question and the correct answer to your question would be what cookiejar said IMO.

If you get 925 at the surface of your aquarium, I hope all you have in it is SPS! I have a feeling no LPS could take that kind of light.... Even if it did, you could count on a bleached out coral.

Someone correct me if I'm wrong and show me links to where people have had such a high output in their aquarium.
Please share links where the ocean has a par of 2500, I believe it, but want to see some articles

 

[Paul_N]

Thats better...but there isnt a certain par value someone can give me?

"I need X PAR to grow acros in my tank."

What is X?

I hear all this talk about the numbers...but it just seems like all relative comparisons without knowing what that means to the corals.

One reason is there is no general consensus on it even from experts. I have to find the site but I also read that if a coral is growing in less than optimal lighting you can compensate by feeding it more.

 

[Paul_N]

Please share links where the ocean has a par of 2500, I believe it, but want to see some articles

Here ya go..:bigsmile:

[FONT=&quot]"The main argument for this is that in nature, the sun illuminates coral reefs with a power of over 100,000 lux (which is a PAR value of about 2600 µE/m2/s)1.[/FONT]"

A new perspective on aquarium lighting

 

[Troylee]

I think you're asking a very broad question and the correct answer to your question would be what cookiejar said IMO.

If you get 925 at the surface of your aquarium, I hope all you have in it is SPS! I have a feeling no LPS could take that kind of light.... Even if it did, you could count on a bleached out coral.

Someone correct me if I'm wrong and show me links to where people have had such a high output in their aquarium.
Please share links where the ocean has a par of 2500, I believe it, but want to see some articles

i ran xm10k, 250watt, lumenarc large reflectors, with a pfo hqi magnetic ballast and got crazy par numbers.... i got 1600 under the lamp... 1200 like 3" down under the waters surface and and 800 to 900 around 12" down and pulled 300 on the sand bed in a 24" tall tank.... granted i bleached most of my stuff with a 6hr photo period lol..... i was running xm20k's before and only had a 3rd of the par on the 10ks*30 to 60 in the sand bed*... my last bleaching effort was my new frag tank when i moved frags from the radium lit display to the shallow t5 frag tank... not sure the par on the frag tank i will have to borrow the meter again from a friend and see i was curious myself....

 

[nayrgaijin]

Here ya go..:bigsmile:

[FONT=&quot]"The main argument for this is that in nature, the sun illuminates coral reefs with a power of over 100,000 lux (which is a PAR value of about 2600 µE/m2/s)1.[/FONT]

A new perspective on aquarium lighting

Paul great article!
Man there is a ton of information on there, time to bring some of it over here!

i ran xm10k, 250watt, lumenarc large reflectors, with a pfo hqi magnetic ballast and got crazy par numbers.... i got 1600 under the lamp... 1200 like 3" down under the waters surface and and 800 to 900 around 12" down and pulled 300 on the sand bed in a 24" tall tank.... granted i bleached most of my stuff with a 6hr photo period lol..... i was running xm20k's before and only had a 3rd of the par on the 10ks*30 to 60 in the sand bed*... my last bleaching effort was my new frag tank when i moved frags from the radium lit display to the shallow t5 frag tank... not sure the par on the frag tank i will have to borrow the meter again from a friend and see i was curious myself....

alas! Crazy output, but bleached corals you say? haha
Man Troy those Lumenarcs OWN don't they?
I am currently debating selling my ATI fixture to go halide :crossedlips:

 

[kingfisherfleshy]

See...I would disagree. Most MH readings come in at over 1000 at the surface (at least that I have been seeing) I have lots of lps, and even some softies...but I grow acros at the top. Those par readings obviously go down the farther down you get in the water column. Finally we are sparking the sort of discussion that I was hoping for!

 

[nayrgaijin]

Do your acros shade alot of the areas where the LPS are?
I think we need a FTS

 

[solitude127]

Here are my readings for my tank

 

[kingfisherfleshy]

Do your acros shade alot of the areas where the LPS are?
I think we need a FTS

No not really...the LPS are on the bottom of the tank though...Ill work on a FTS sometime this week.

Solitude...those are pretty low values...is that a milli up top? My experience with milli's in the past has been that they (general again, I know) can get away with less light than the acros. But still 500 PAR seems like nothing when these guys are growing their acros in 1100-1200 PAR.