It is always par par par

[gearhead]

I have done some research on lighting and I have found that dli or daily light index is More important in my eyes than actual par. For example, if I run my sand bed at 160 par for a total of 9 hours that makes my dli about 5. If it is 120 par for 12 hours it is also around 5. I have found that if I run higher par less on time it helps with algae. What I would like to see if people will share their dli and their type of coral. My lps on the sand bed has dli of about 4 for my lps. My sps is getting about 9. I have read some research papers that showed that in the wild some sps were receiving a dli of 30. I think this is the key to getting it right. Keep in mind if your lighting is ramping to your peak par that can't be counted because the formula only works if the values are constant. Here is the dli calculator.

Free Daily Light Integral (DLI) Calculator - ScynceLED

Check your Daily Light Integral with our free DLI Calculator to gain insight on how much light is available for your plants.

scynceled.com

 

[cvrle1]

Another caveat to add to this is that corals can absorb light for 4 hours only, or so did several papers/articles say before. If you take that into consideration with DLI, then you want as much PAR as possible for those 4 hours, so that your DLI is as high as possible.

This is way outside of my scope of knowledge, but I would rather have higher PAR for shorter period than lower par for long period of time.

 

[gearhead]

That is interesting.

 

[ReefGeezer]

PAR can be a measure of a photons in a limited spectrum or all photons available according to the meter used. It may or may not be the spectrum corals need. Corals roughly use near UV to blue and some red. The measurement of these photons is referred to as "PUR". Algae might use more yellow that is more prevalent in white, warm white, and green LEDs, along with the red portion of the spectrum.

I have read that corals become saturated after a given time at given PAR/PUR conditions. I don't know how to measure that so i shut off my lights in the middle of the day. I have two 5 hour lighting periods separated by a dim period. If nothing else, it allows me to see and feed the fish early in the morning, before I leave for work, and while I'm home after work. Kinda sucks on the weekend though.

I'm getting ready to install a controller that will let me ramp the color groups up & down via a program. I hope this will eliminate the need for the dim period and further reduce algae growth.

 

[xiaoxiy]

Out of curiosity, Can one of you guys link me the source/study that shows that corals can only absorb light for 4-5 hours a day?

@Dana Riddle. Do you know of any studies that look at coral photosynthesis as a function of light duration?

 

[gearhead]

I understand the spectrum for sure I run ab+ with a twist whites for 4 then all blue in the last 5 hours. With my gen 4 radion pros. I switched from Kessel and what a difference in my corals. never heard of corals only absorbing light for four hours though.

 

[Dana Riddle]

Out of curiosity, Can one of you guys link me the source/study that shows that corals can only absorb light for 4-5 hours a day?

@Dana Riddle. Do you know of any studies that look at coral photosynthesis as a function of light duration?

The notion that corals (or correctly, their zoox) can only absorb light for 4-5 hours a day seems to be a misinterpretation of available data. I don't have a reference off the top of my head about a peer-reviewed paper (that is, absorption of light after saturation/photoinhibition is reached.) I'd have to go through my references... But, a generalization goes like this. If light intensity is below the photosaturation point, zoox will absorb light for use in photosynthesis no matter the photoperiod. If the photoinhibition point is reached, photosynthesis might continue, with excess energy dissipated as chlorophyll fluorescence and non-radiant heat. There is some evidence that photosystem II can uncouple from PSI, at least in some cases. Then fluorescence/reflectance of colorful proteins come into play. But the short answer is, zoox can, in many cases, absorb light energy as long as it is available. Clear as mud, right?

 

[xiaoxiy]

The notion that corals (or correctly, their zoox) can only absorb light for 4-5 hours a day seems to be a misinterpretation of available data. I don't have a reference off the top of my head about a peer-reviewed paper (that is, absorption of light after saturation/photoinhibition is reached.) I'd have to go through my references... But, a generalization goes like this. If light intensity is below the photosaturation point, zoox will absorb light for use in photosynthesis no matter the photoperiod. If the photoinhibition point is reached, photosynthesis might continue, with excess energy dissipated as chlorophyll fluorescence and non-radiant heat. There is some evidence that photosystem II can uncouple from PSI, at least in some cases. Then fluorescence/reflectance of colorful proteins come into play. But the short answer is, zoox can, in many cases, absorb light energy as long as it is available. Clear as mud, right?

Thanks for the clarification and response!

 

[gearhead]

Thanks

 

[chicago]

Very interesting... gearhead..bit off topic.. but you found the radions allowed corals to appear better...or better growth and more over all with the radions.. i have a bank of 6 but they are the 3gen... I was thinking of supplementing with two kessels but how thinking no...

 

[Nano sapiens]

What I would like to see if people will share their dli and their type of coral. My lps on the sand bed has dli of about 4 for my lps. My sps is getting about 9. I have read some research papers that showed that in the wild some sps were receiving a dli of 30. I think this is the key to getting it right. Keep in mind if your lighting is ramping to your peak par that can't be counted because the formula only works if the values are constant. Here is the dli calculator.

I have seen this first hand when snorkeling in an LPS dominated cove in Palau where the surrounding hillocks allowed for only around 3-4 hours of direct light and the rest of the day was similar to ambient lighting intensity. Outside of the cove, Acropora thickets received the full intensity and an obviously much higher DLI due to lack of obstructions.

While I'd like to share a DLI, like many I use an LED array that ramps, so would need a data logger to get an accurate number.

 

[Dana Riddle]

DLIs in my tanks have been ~5 to 7.7 at the sand bed. A Strawberry Shortcake Acro grew wonderfully in the latter amount of light. DLIs can be calculated in ramped lighting, but it takes a data logger (such as the Apex PAR sensor or an Apogee quantum meter) or a very dedicated hobbyist taking measurements at each increment.

 

[chicago]

MX-200 Apogee is what I have . Not sure how to use to calculate DLI

 

[Dana Riddle]

MX-200 Apogee is what I have . Not sure how to use to calculate DLI

Your meter logs an average of 60 measurements every 30 minutes. Multiply each 30-minute average by 1800 (the number of seconds in a 30 minute period.) Repeat this procedure for each 30 minute interval and sum them. Divide by 1,000,000 and - voila - you have the Daily Light Integral (DLI.)

 

[chadfish]

Out of curiosity, Can one of you guys link me the source/study that shows that corals can only absorb light for 4-5 hours a day?

@Dana Riddle. Do you know of any studies that look at coral photosynthesis as a function of light duration?

It’s a bit late, but this article seems to address all of the questions in this thread.

Diel versus time-integrated (daily) photosynthesis and irradiance relationships of coral reef organisms and communities

The most important source of energy to tropical shallow water coral reefs is light, the transformation of which ultimately limits reef biomass and growth. Therefore, measurements of productivity (primary production, P) for benthic reef organisms and communities ...

www.ncbi.nlm.nih.gov

@Dana Riddle is correct, corals seem to have a PAR saturation point and a point after that where more par actually reduces photosynthesis. On average, though, the more DLI, the more photosynthesis; it’s linear, but each species has its own saturation points.

This article comes with links to data which I strongly suggest you check out. Most species listed are important reef-builders, not for home use, but the overall principle hold true.

 

[Dana Riddle]

It’s a bit late, but this article seems to address all of the questions in this thread.

Diel versus time-integrated (daily) photosynthesis and irradiance relationships of coral reef organisms and communities

The most important source of energy to tropical shallow water coral reefs is light, the transformation of which ultimately limits reef biomass and growth. Therefore, measurements of productivity (primary production, P) for benthic reef organisms and communities ...

www.ncbi.nlm.nih.gov

@Dana Riddle is correct, corals seem to have a PAR saturation point and a point after that where more par actually reduces photosynthesis. On average, though, the more DLI, the more photosynthesis; it’s linear, but each species has its own saturation points.

This article comes with links to data which I strongly suggest you check out. Most species listed are important reef-builders, not for home use, but the overall principle hold true.

It's not the duration of light as it is intensity. See here:

How Much Light?! Analyses of Selected Shallow Water Invertebrates’ Light Requirements

Dana examines the optimal amounts of light required for select stony corals, soft coral and a Tridacna clam, and is intended to complement his previous article 'Too Much Light!' (July 2004).

reefs.com

 

[chicago]

Your meter logs an average of 60 measurements every 30 minutes. Multiply each 30-minute average by 1800 (the number of seconds in a 30 minute period.) Repeat this procedure for each 30 minute interval and sum them. Divide by 1,000,000 and - voila - you have the Daily Light Integral (DLI.)

Dana... I guess I will look up and find a manual... not sure how to do this.. as I have always just used it for a few min at a time... now doing a bunch of research on this unit... and seeing that it needs to be manipulated for the blue.. ect.,.. add 15% to the reading.. intersting thing is ... i have also the unit from apex.... and that always reads less when compared to the MQ-200.... and if I am adding more to the MQ-200 reading.. we are talking about ... well... i just did a read... morning reef light is mQ-200 = 40 X 1.15 = 46 ... but my APEX is saying 3 - it is clean and nothing blocking it... . ( I am using the MQ-200 in the Electric Mode)

 

[Dana Riddle]

Is the Apex PAR sensor configuration set at '1' for minimum and, say, '500' for maximum?

 

[chicago]

just checked... and yes Dana set at 1 and 500

 

[Dana Riddle]

I use the MQ-510, and the results from the Neptune PAR sensor are practically identical. Facebook has a Neptune Systems page, and the experts can help you there. Also, have you tried the clear sky calculator from Apogee to see if your MQ is calibrated?
www.clearskycalculator.com