[Timezone Detection]
Create Account - Join in Seconds!

User Name: Email Address:
Human Verification

Please enter the six letters or digits that appear in the image opposite.

Par or not to par that is the question


Bookmark and Share
Results 1 to 8 of 8
  1. #1
    SaltCreeps - Reefkeeper CR Member
    Join Date
    Nov 2010
    Location
    Saginaw MI
    Posts
    103
    First Name
    chuck

    Default Par or not to par that is the question

    Please read evils post just below



    Yesterday another reefer and i were talking about leds and he told me that the PAR was no good with leds. my response to him was Par is over rated not that it is totally unimportant just that it was made to help land plants grow not corals. corals and plants have had hundreds of thousands of year(minimum) to evolve from each other and use light in similar and different ways. Corals for one use a much wider spectrum of light from 6,500k-30,000k and most plants use mainly 6,500k-14,000k as they can absorb larger quantities of this high energy light. basically corals use a wider range of light than what a par meter reads making it a useful tool but not a reefs law. It is also stated in a few articles that we are yea to totally understand the full spectrum of light that is used by the symbiotic algae in corals for there are so many, and i would have to guess a lack of funds to to the project thoroughly
    please leave a response

    Please read these
    [ame]http://en.wikipedia.org/wiki/Photosynthetically_active_radiation[/ame]
    http://sa.rochester.edu/jur/issues/spring2005/li.pdf
    Quotes of interest
    Photosynthetically active radiation, often abbreviated PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye.Other living organisms, such as green bacteria, purple bacteria and Heliobacteria, can exploit solar light in slightly extended spectral regions, such as the near-infrared
    In “clear” seawater, PAR reduces to 1 percent of its incident value within 100 m. This metric is called the euphotic depth. Spectral distribution plots show that due to slight turbidity changes in different waters, the euphotic depth can extend from over 200 m to less than 40 m. This depth range is labeled as the euphotic zone.6 Because of coral’s PAR requirement, we may conclude growth promotion is the greatest in clearer waters (greater euphotic zone). Smith and Baker conducted research on the inherent optical properties of natural waters.
    Inherent Optical Properties of Various Seawaters
    The amount of photosynthesis available radiation (PAR) and harmful radiation are responsible for a coral’s health. PAR consists of wavelengths between approximately 0.4 to 0.7 microns. Because no precise data on the action spectrum of different corals (more precisely their symbiotic zooxanthellae) are known, we cannot yet quantitatively correlate dynamics in a coral varietie’s response to different wavelengths within both for the clearest natural seawaters.
    Last edited by SaltCreeps; 01-19-2011 at 04:37 PM.

  2. #2
    CR Member
    Join Date
    Dec 2010
    Location
    Lansing, MI
    Posts
    28

    Default Fluval Edge, Corals & LEDs

    I'm not sure you can unequivocally state that LEDs do not provide enough PAR for corals. That is simply not true. I used our club's PAR meter recently to test the two MR16 LEDs that I put in my Fluval Edge to replace the two MR11 Halogens that came with it. These LEDs were rated at 5,000 - 7,500K @ 330 lumens each.

    http://fluvaledgeproject.shutterfly.com

    At the bottom of the tank, under the LEDs, the PAR reading was 200. At the top of the tank, just under the water, the PAR reading was around 500. Out of the tank and under the LED, the reading was around 2,400 PAR units.

    Compare this with the 18W PC that is also on the tank. This produces about 120 PAR on the bottom of the tank under the PC. At the top of the tank, just under the water, the PAR reading was around 300. Out of the tank and under the PC, the reading was around 500.

    I have recently ordered a custom LED setup from Nanotuners that is specifically made for the Fluval Edge. It will have 3 stips, 6 x 3W LEDs for each strip. It's 54W and will produce at least 1400 lumens. I will let you know what the PAR readings are once I get it.

    I currently have some Zoas, Duncans, Frogspawn and an Acro all doing well.

    Overall, I would have to say that some LEDs are definitely not for the reef aquarium but it's probably more a case of quality and quanity.

  3. #3
    SaltCreeps - Reefkeeper CR Member
    Join Date
    Nov 2010
    Location
    Saginaw MI
    Posts
    103
    First Name
    chuck

    Default

    yes i agree with you but for most led setups for saltwater are between 10k and 20k and under a par meter they do not give you the depth that a halide ore even t5's will(this was the point some else was making to me).
    what im saying is a par meter doesn't read all of the light and its is the spectrums of light that penetrate the water deepest aka blues. i guess my point is a par readings needs to be taken with a grain of salt as they are not the entire story for how corals use light for produce food.

    i too grow lots of sps under my leds

  4. #4
    evilc66 - Reefkeeper CR Member
    Join Date
    Jan 2010
    Location
    Shelby Twp. MI
    Posts
    297

    Default

    Saying that PAR readings (at least with Apogee Quantum meters) should be taken with a grain of salt is a good point, but most everything else that was posted in the OP, really isn't that accurate.

    First off, color temperature is an extremely poor way of characterizing light of any description, outside of it's visual appearance. A 10,000K light can be made with hundreds of different spectral qualities, each of which will produce different PAR readings. Wavelength is far more critical to growth, regardless of it being marine or terrestrial. Both plants and corals use chloropyll A and B to convert light to sugars. The only difference is in how much the rely on one over the over. Chlorophyll A is more red biased (useful for plant flowering cycles), while chloropyll B is more blue weighted, and more useful for our corals that don't see nearly as much red light. That's not to say red light isn't useful. The shallower the water, and the coral collection depth (read: sps), the more red light the corals see.

    Ok, so PAR readings using an Apogee meter may not be the most accurate, but many times, repeatability is more important that absolute accuracy. As long as the numbers recorded by such a device aren't taken as gospel, and used as a comparitive reference, then they are still very valid measurements. Sadly, as hobbyists, we don't normally have access to tools that will produce better results. Spectrometers can read and partition off ranges of the visible spectrum (keep the useful parts, ditch the not so useful parts) so that PUR (photosynthetic useable radiation) can be calculated, but those run into the many thousands of dollars. Now, even PUR is a subjective measurement, and I'm pretty sure that no standard of measurement exists for our application. I know there is a certain "internet blogger" that claims PUR is the be all and end all of light measurements, but he has no idea what that even means.

    Spectrally, LEDs, cool white ones in particular, are almost perfect for coral growth. Their emission peaks are almost dead on the photosynthetic peaks of chlorophyll B. Blue LEDs are basically pure PAR. Anyone that tells you that LEDs aren't suitable for coral growh, at any depth, has no idea what LEDs can do. I know there have been many discussions on various forums about at what depth LEDs aren't useful any more, and that you should use large MH setups for deep tanks. Well, I'm here to tell you that is a bunch of crap. I built a fixture recently that should match most 1000W MH setups in terms of peak PAR, but only consuming less than 200W. I hit 1500 PAR at 18". 300 PAR at 48". It's all about using the right LEDs with the right optics.

    Also, to say that coral species photosynthetic action response curves don't exist is non-sense. There are hundreds of research studies out there that characterize the photosynthetic response of many of the commonly found corals species that we see on a daily basis. I'll post a few if anyone is interested.

    I guess what I'm getting at here is that PAR measurements are still useful, to a degree, and certainly more useful than Lux or Footcandle measurements (measures light based on human eye response). They just have to be used in context. Also, don't beleive all that you read or hear about the proper ways to measure and characterize light. There are many people that think they have an understanding of it, but unless you work in the aquarium lighting world (like me), or are way more into coral biology than the average hobbyist, then they probably don't know the whole story. Light is a very complex subject

  5. #5
    MizTanks - Reefkeeper
    Join Date
    Oct 2009
    Location
    U.P. of Michigan.
    Posts
    8,444
    First Name
    Jamie
    Awards Photo of the Month - October 2012 Photo of the Month Post and Reply Award - Winner of the first PAR Contest. Monthly Giveaway Winner

    Default

    Wow, what an awesome read! As a newb I even understood most of what you've explained here. Quit the feat ill tell you
    As a newb I have one question. If I cannot afford an LED fixture, in a fixture of t5ho's 4x24 in a 26g bow front. What would be the best combination of bulbs to run to give the corals most of what they would need to be healthy?


    There is nothing like being a REEFER!
    There's nothing like being a Reefer! www.upmmas.com

  6. #6
    jimsflies - Reefkeeper
    Admin/Founder

    Join Date
    Aug 2009
    Location
    Michigan
    Posts
    11,467
    First Name
    Jim

    Default

    Jamie - Created a new thread with your T5 question here to keep this thread on topic.

  7. #7
    SaltCreeps - Reefkeeper CR Member
    Join Date
    Nov 2010
    Location
    Saginaw MI
    Posts
    103
    First Name
    chuck

    Default

    i just wanted to say thank you evil ,for that reply. i certainly do not know light to the depths of you but you hit the nail on the head on where i was going with it.

  8. #8
    evilc66 - Reefkeeper CR Member
    Join Date
    Jan 2010
    Location
    Shelby Twp. MI
    Posts
    297

    Default

    With LEDs being the hot topic of discussion over the last few years, more and more people have been digging into the mechanics of light, and what we really need. It's funny that it took this technology for the majority of reefers to start questioning things more. But, with all this discussion, there is a lot of mis-information, and half truths being thrown around, which is why I reply to threads like this. I'm all for people learning out the technology, but know what you are talking about if you are going to discuss it, or worse yet, bash a technology because you don't know enough about it. Saltcreeps, none of this is aimed at you, as you innocently started the conversation based on information that you were given. Guys like me have volunteered a ton of information regarding LEDs, light, and it's interaction with corals, so it shouldn't be hard to find out what you need. Never the less, discussions like this end up educating everyone, and I'm all for that, even though the genesis of the conversation didn't start on the right foot

Similar Topics

  1. Trace Elements RO and DI question
    By EMUreef in forum Chemistry
    Replies: 7
    Last Post: 03-25-2013, 10:17 AM
  2. Sps question.
    By MizTanks in forum Small Polyp Stoney (SPS) Coral
    Replies: 2
    Last Post: 09-03-2012, 11:36 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

About CaptiveReefs

    If you are interested in learning about reefkeeping or have a problem with your reef, our reefkeeping community is here to help. Feel free to ask a question or search our site. We have lots of experienced reefkeepers that are willing to provide free reefkeeping advice!

    Besides being a great resource for all levels of reef aquarium hobbyists, CaptiveReefs is a social experience that will enhance your enjoyment of reefkeeping. CaptiveReefs is committed to connecting reefkeepers with the support and information they need to grow beautiful coral reef aquariums.

Information

Connect with Us