PAR rant

[Scott.h]

I'm glad I have a good par meter. It takes the guess work out of it. I can see a healthy fully extended acro in the lfs, stick my meter next to it, and replicate what it's used to when I get home. As well as get the most out of my bulbs. I have too much money in this hobby not to utilize all the tools available. As far as spectrum goes, I rely on common sense and the bulb manufacturers. So far so good.

 

[saltyfilmfolks]

I'm glad I have a good par meter. It takes the guess work out of it. I can see a healthy fully extended acro in the lfs, stick my meter next to it, and replicate what it's used to when I get home. As well as get the most out of my bulbs. I have too much money in this hobby not to utilize all the tools available. As far as spectrum goes, I rely on common sense and the bulb manufacturers. So far so good.

+10000000000000000

 

[mcarroll]

There is a point where a particular coral will receive all of the "light" that it needs, anything additional to that, and it just becomes counterproductive.

The "light compensation point" is what you're referring to. The counterproductive part is highly variable though, as not all corals are equally adept at dealing with the stresses of photosynthesis under all circumstances.

You know I recently discovered that in the world of terrestrial plants their professionals have several "plant trait databases" that catalog things like the compensation point for what at least seems to be all known plants. It could be all known crop plants, but whatever the case these databases look big and comprehensive. WOW to have something like that for coral.

I reckon that corals can adapt more readily to different light than to different (poor) water quality or a lack of suitable flow.

You aren't wrong about their adaptability – photosynthetic corals are completely amazing in the truest, cosmic sense of the word; if any critter deserves to be called a magician, it's them for what they do with light – but their adaptability is intimately linked to the nutrient and flow regimes they are exposed to.

It just so happens that, generally speaking, they are very adaptable on all three fronts.

You might like these for more reading:

• Results of the 1991 United States-Israel Workshop, “Nutrient Limitations in the Symbiotic Association between Zooxanthellae and Reef-building Corals”
• Ratio of Energy and Nutrient Fluxes Regulates Symbiosis between Zooxanthellae and Corals
• Is the coral-algae symbiosis really ‘mutually beneficial’ for the partners?
• Poke around the "Light" and other sections of my blog some more too.

 

[mcarroll]

So while on the subject of light, how long do you leave your lights on per day? Do you leave it as a constant or does your light gradually decrease through the day? I leave mine on for 12 hours and thinking of cutting it to 10 after reading these posts.

A 12 hour day should be fine if you have a sunrise/sunset dimmer situation going on. I don't know I'd say it's required at all though....so if you want shorter I bet you wouldn't have a problem.

If your lights just come on at max. intensity and stay there all day, then you should consider what intensity that light is, and depending on the answer (how many lux or PAR?), you might definitely want to shorten the day to as little as five or six hours.

 

[Surfandturf]

A 12 hour day should be fine if you have a sunrise/sunset dimmer situation going on. I don't know I'd say it's required at all though....so if you want shorter I bet you wouldn't have a problem.

If your lights just come on at max. intensity and stay there all day, then you should consider what intensity that light is, and depending on the answer (how many lux or PAR?), you might definitely want to shorten the day to as little as five or six hours.

So I have an AI prime light fixture for my 10gal. I have it set up to gradually increase the blues until it peaks at noon, I have it level off at the peak for about 6 hours and then it slowly declines until lights off. I have the UV, Red, and Green all under 10% the entire time. The White lights I keep at 16%at the peak down to 8% the last few hours before the lights go out. One of the things that I find interested with this light fixture is the UV light. I am wondering if this is actually giving UV or what it is doing. I feel like turning it off for a week and seeing what if anything it does. Another interesting note about this light system is that it does allow me to change the kelvin rating that of the light, but if I choose to change the spectrum of the lights (more blue, less white) it will reset the kelvin rating and not give me the reading for my personal light setting.

 

[saltyfilmfolks]

change the kelvin rating that of the light, but if I choose to change the spectrum of the lights (more blue, less white) it will reset the kelvin rating

color temp and spectrum. same thing.

not give me the reading for my personal light setting.

dumb light

 

[SB Reef Lights]

Just a thought on PUR verse PAR. Take folks putting my retrofit PCB boards in a MarsAqua. Most folks have to drop intensity 15%. Nothing changed in the number of diodes or power, just wavelength of the diodes. Folks turn down 15% and get better growth and color development. Yet the MarsAqua stock will show slightly more PAR on a typical meter, while PUR as a percent of PAR is lower. Lots of wasted energy in wavelengths that have much less benefit to the corals.

Comparing PAR from tank to tank and light to light does not tell the whole picture. Now using a PAR chart to compare different locations in the same tank and light is somewhat useful. For example 2 standard 75G tanks with the same 250w Radium over each side. Both tanks could share on PAR map. As stated above, you're corals never lie. Watching them is the best measurement of whether they are getting the correct wavelengths and intensities.

As far as aesthetics, it's mostly personal choice. Most seem to enjoy a blue bias with enough CRI for yellows and reds to look yellow and red, rather than washed out. But there is no correct answer.

 

[mcarroll]

One of the things that I find interested with this light fixture is the UV light. I am wondering if this is actually giving UV or what it is doing. I feel like turning it off for a week and seeing what if anything it does.

Considering what you paid for those extra emitters, I think I'd be less happy/exited than you about turning them down/off.

I agree it's debatable whether UV is worth anything to the corals.....think longer term for any experiments though. It would take time for corals to completely adapt and normalize so you could see all differences..

Without doubt UV is not good for your eyeballs.

Another interesting note about this light system is that it does allow me to change the kelvin rating that of the light, but if I choose to change the spectrum of the lights (more blue, less white) it will reset the kelvin rating and not give me the reading for my personal light setting.

Those kelvin ratings are just labels in the software for the setting you are using....I wouldn't even expect them to be accurate to the color being produced.

Unless you like one of the presets (which kinda defeats the purpose of such a controllable light in my opinion) just set the colors how you like them and then (get and) use a light meter to set your intensity. If you make intensity changes, remember to keep them smaller than 2000 lux and wait at least a few weeks between changes.