PAR

[jtl]

There is always a lot of conversation about what light but I find very little about "what PAR". I have read and heard that less is better, even for SPS. I believe BRS recommends 250-350 and WWC says 225-300 for SPS and less than 100 for LPS. What do you recommend? I got the impression based on a talk that Dana Riddle did once that he recommended lower PAR levels, high water flow and higher than normal Alk.

 

[BigRich]

There is always a lot of conversation about what light but I find very little about "what PAR". I have read and heard that less is better, even for SPS. I believe BRS recommends 250-350 and WWC says 225-300 for SPS and less than 100 for LPS. What do you recommend? I got the impression based on a talk that Dana Riddle did once that he recommended lower PAR levels, high water flow and higher than normal Alk.

For me/my research, it’s a Pandora’s box in the sense it’s really relative to your tank. If you are running a ULNS you want lower ALK, and possibly lower side of PAR but then you can get away with higher PAR if you increase flow. It’s almost like jenga or a constant moving puzzle. One adjustment can affect everything else. I would always say start lower on PAR and adjust higher slowly. One thing I’ve learned about this hobby is slow is fast!

 

[Oldreefer44]

First of all need to know what it is you are trying to grow. Different corals need different light intensities just like plants. Also, there are numerous threads that talk about PAR including ones from Dana. If less PAR were the goal then manufacturers and hobbyists would not be on a continuous quest for more of it.

 

[jtl]

I have a mixed reef, some sps and mostly lps, no softies unless you consider RFA a soft coral.

Maybe higher output sells lights but that doesn't mean it is always necessary. Most people that I know don't even run their lights at close to 100%. We try to place our SPS to get ~250 and about the lowest we can do for LPS is 150.

 

[BestMomEver]

I’m not an expert on lighting but my Radions are one of the pieces of equipment I have the most confidence in. Other than that, I totally agree with @Randy Holmes-Farley .... my water flow is about 90x tank volume per hour (give or take) and I run about 10.2 dkh.

 

[jtl]

I’m not an expert on lighting but my Radions are one of the pieces of equipment I have the most confidence in. Other than that, I totally agree with @Randy Holmes-Farley .... my water flow is about 90x tank volume per hour (give or take) and I run about 10.2 dkh.

What is your PAR top and bottom?

 

[Firemanreefkeeper]

I have 225 par in my tank at the very top. Most of my corals are in 190 or less. I have the aquatic life t5 led hybrid light. Kessil Ap700 is my LED and its at about 6% so i can raise it higher but my corals grow well. My tank is 8.4 alk, 440 cal 1400 mag. +/-25ppm nitrates. 35ppb phosphate. I have maxspec gyre pumps that do about 25x turnover. Tank is mixed but I'd say it's 2 pieces of SPS to 1 LPS or zoa.

 

[jtl]

I have 225 par in my tank at the very top. Most of my corals are in 190 or less. I have the aquatic life t5 led hybrid light. Kessil Ap700 is my LED and its at about 6% so i can raise it higher but my corals grow well. My tank is 8.4 alk, 440 cal 1400 mag. +/-25ppm nitrates. 35ppb phosphate. I have maxspec gyre pumps that do about 25x turnover. Tank is mixed but I'd say it's 2 pieces of SPS to 1 LPS or zoa.

Good info! My NO3 and PO4 are WAY lower like 1 and .01.

 

[BestMomEver]

What is your PAR top and bottom?

Probably about 300 +/- at the top and 90-120 at the bottom. My Biocube has Steve’s LEDs and runs close to 500 + at the top. My nems love it!

 

[Johnson556]

3 XR30 G4 Pro’s at 40% and 4x80Watt T5’s

Here’s my values, tank is all SPS and Zoas

 

[Firemanreefkeeper]

Good info! My NO3 and PO4 are WAY lower like 1 and .01.

I'm not happy with the 25ppm. I've got a lot of buildup in sump, sand bed, overflow I'm working to get rid of. My coral doesn't hate, it's more me.:)

 

[Bpb]

This is far more complicated than BRS and WWC lead on. They post those as general guidelines of par levels that are appropriate for a mixed tank, especially under the notion that nutrients are kept low. In ultra low nutrient tanks, lower par levels are essential. Higher alkalinity levels are also somewhat helpful for pigment development in soft corals and lps....the ones that dominate the hobby.

Light levels, nutrients, and alkalinity are levers that need to move simultaneously. Ryan at BRS mentions this specifically in one of those videos but that is a tidbit people forget because they just jump to the conclusion at the end.

No matter how you run your tank you are making an effort somewhere to achieve one of those where you want it. You’re either spending more money on electricity and light wear and tear to get par up, and letting nutrients relax into a higher range, or you’re saving money on lower lighting, but putting a ton of effort into nutrient control.

Dana Riddle’s presentation on Hawaiian porites has probably been misinterpreted worse than any piece of data I’ve seen released in recent years. That stuff will grow by candlelight. You can’t equate the demands and tolerances of shallow water Indonesian or Australian acropora, to a deep water soft coral, or in this case a particular species of porites. Genetically they will have different thresholds of photoinhibition.

Lastly, par between light forms is not generally received equally by corals. Try to pump 500-700 par from Kessils into a tank and see how everything grows. Most people I see on here tune them to 100-200 par even for sps tanks. I presently have 1100 at the water surface, anywhere between 400-700 mid way up in the tank depending on where the reading is taken, and between 200-300 on the sandbed.

 

[Charlie’s Frags]

Dana has recommended at least 200 par for acropora even up to 800 par for certain acropora in another thread.

 

[jtl]

This is far more complicated than BRS and WWC lead on. They post those as general guidelines of par levels that are appropriate for a mixed tank, especially under the notion that nutrients are kept low. In ultra low nutrient tanks, lower par levels are essential. Higher alkalinity levels are also somewhat helpful for pigment development in soft corals and lps....the ones that dominate the hobby.

Light levels, nutrients, and alkalinity are levers that need to move simultaneously. Ryan at BRS mentions this specifically in one of those videos but that is a tidbit people forget because they just jump to the conclusion at the end.

No matter how you run your tank you are making an effort somewhere to achieve one of those where you want it. You’re either spending more money on electricity and light wear and tear to get par up, and letting nutrients relax into a higher range, or you’re saving money on lower lighting, but putting a ton of effort into nutrient control.

Dana Riddle’s presentation on Hawaiian porites has probably been misinterpreted worse than any piece of data I’ve seen released in recent years. That stuff will grow by candlelight. You can’t equate the demands and tolerances of shallow water Indonesian or Australian acropora, to a deep water soft coral, or in this case a particular species of porites. Genetically they will have different thresholds of photoinhibition.

Lastly, par between light forms is not generally received equally by corals. Try to pump 500-700 par from Kessils into a tank and see how everything grows. Most people I see on here tune them to 100-200 par even for sps tanks. I presently have 1100 at the water surface, anywhere between 400-700 mid way up in the tank depending on where the reading is taken, and between 200-300 on the sandbed.

I agree, this hobby is complicated and there are many approaches and little agreement. My most recent chemistry readings are NO3 at 2, PO4 at .040, Ca 450, Alk 8, Mg 1340, temp 78, pH 8.2, salinity 35pts. I don't own a PAR meter so I use the readings and calculator that Reefbreeders provided for my light fixture, not perfect for sure, but close enough given all the other variables. My takeaway from the BRS, WWC and Dana's presentation is that corals will grow nicely at lower par levels than I previously thought.

 

[Bpb]

I agree, this hobby is complicated and there are many approaches and little agreement. My most recent chemistry readings are NO3 at 2, PO4 at .040, Ca 450, Alk 8, Mg 1340, temp 78, pH 8.2, salinity 35pts. I don't own a PAR meter so I use the readings and calculator that Reefbreeders provided for my light fixture, not perfect for sure, but close enough given all the other variables. My takeaway from the BRS, WWC and Dana's presentation is that corals will grow nicely at lower par levels than I previously thought.

True. Based on data the threshold for minimum levels of light needed to engage photosynthesis is much lower than people once believed necessary...beyond that though, the light levels for photoinhibition are much higher for many sps than people are understanding based on some recent videos released. It’s a range. Not simply put “you can grow X Coral in 200 par”. It’s more of, you can sustain life in as low as 150 par for X species and it can tolerate way up to 800 par. The kicker here is more light+more building blocks = faster growth to a point if nutrients and elements are in ideal ranges. So it’s not simply “if you can grow it in 200 par you’re wasting your energy giving it 500.” It’s not that cut and dry. If you are able to correctly manipulate flow and nutrients, you can speed up growth and draw more vibrant colors out by increasing light levels within an acceptable range

 

[jtl]

True. Based on data the threshold for minimum levels of light needed to engage photosynthesis is much lower than people once believed necessary...beyond that though, the light levels for photoinhibition are much higher for many sps than people are understanding based on some recent videos released. It’s a range. Not simply put “you can grow X Coral in 200 par”. It’s more of, you can sustain life in as low as 150 par for X species and it can tolerate way up to 800 par. The kicker here is more light+more building blocks = faster growth to a point if nutrients and elements are in ideal ranges. So it’s not simply “if you can grow it in 200 par you’re wasting your energy giving it 500.” It’s not that cut and dry. If you are able to correctly manipulate flow and nutrients, you can speed up growth and draw more vibrant colors out by increasing light levels within an acceptable range

I am not worried about energy use, LED's are so efficient it hardly makes a dent in my electric bill but I am worried about bleaching. The whole point of me starting this thread is while our corals are sustaining, they are not as colorful as they once were so my wife convinced me to lower the par, in retrospect perhaps I should have raised the par. It has only been a couple of days so I can easily go back and move it up. For example, par at the top of my rocks ( 6" below the waterline) averaged 229, at mid level par was 170 and at the sand it was 137. I have probably 70 corals and most are living in a par range of 200 to 154, this is certainly not on the high par side.

 

[jda]

You have to factor in the kind of light if you want to compare PAR. Most LED will burn coral if you get much above 350, but with VHO, T5, MH and even PCs, you could double this without any kind of burn - this is likely a quality thing over a quantity thing.

I also think that low-par when combined with low building blocks is also mostly a LED thing. I run up to 750 PAR under my MH and my N is .1 and my P is usually .005 to .01.. so ocean-level low. I have no issues. However, my theory that LED produce too much of some bad spectrum would support the theory that with a lower number of building blocks available for tissue repair, that you need to keep the harmful waves from LED lower in this instance. This does not matter with the other forms of lighting when the coral can handle all of the good light that you can give it.

While many corals can live with less PAR, it has always been my experience that they can do better with more. I do use mostly MH and some T5s and VHOs, to the quality is good.

In general, you have to factor in quality when you factor in quantity.

 

[Bpb]

I am not worried about energy use, LED's are so efficient it hardly makes a dent in my electric bill but I am worried about bleaching. The whole point of me starting this thread is while our corals are sustaining, they are not as colorful as they once were so my wife convinced me to lower the par, in retrospect perhaps I should have raised the par. It has only been a couple of days so I can easily go back and move it up. For example, par at the top of my rocks ( 6" below the waterline) averaged 229, at mid level par was 170 and at the sand it was 137. I have probably 70 corals and most are living in a par range of 200 to 154, this is certainly not on the high par side.

I gotcha. I think you’re in the safe range really. While a wavelength doesn’t change based on what produces it, and a photon is a photon, cumulative par levels among different light sources don’t seem to be equally effective as JDA mentioned. I tend to agree with him. I too am running has high as 600-700 for some corals in the tank (I have a montipora receiving close to 1000 par actually), and I would not DREAM of delivering that kind of par with Kessils or radions. The 200-350 range recommendation is closer to in line with what LEDs should be targeted for. Not saying better or worse, just as a general fact based on a large set of user experience reports.

 

[jtl]

You have to factor in the kind of light if you want to compare PAR. Most LED will burn coral if you get much above 350, but with VHO, T5, MH and even PCs, you could double this without any kind of burn - this is likely a quality thing over a quantity thing.

I also think that low-par when combined with low building blocks is also mostly a LED thing. I run up to 750 PAR under my MH and my N is .1 and my P is usually .005 to .01.. so ocean-level low. I have no issues. However, my theory that LED produce too much of some bad spectrum would support the theory that with a lower number of building blocks available for tissue repair, that you need to keep the harmful waves from LED lower in this instance. This does not matter with the other forms of lighting when the coral can handle all of the good light that you can give it.

While many corals can live with less PAR, it has always been my experience that they can do better with more. I do use mostly MH and some T5s and VHOs, to the quality is good.

In general, you have to factor in quality when you factor in quantity.

There may be truth to what you believe in terms of spectrum. With leds we have the ability to not only control intensity but also lots of spectrum choices. I think for the most part we go for the visual effect but who knows if this is the best combination of colors. I can control Red at 660nm, Green at 520nm, Royal Blue at 450nm, Neutral White at 5500K, Cool Blue at 480nm and Violet at 420nm. I don't use Green and very little Red so most of what I get is in the range of 420nm to 480nm with max power of 220 watts. Then there is the issue of lens dispersing the light. It is no wonder there is no one single answer.

 

[Charlie’s Frags]

I run LED only, hydra 52 HD’s, and all my tenuis are receiving 400-600 par with zero burning and I have 300-350 par on the sandbed where my zoas, smooth skins, monti’s and lps are, again with zero burning. My setup has the fixtures 16” above the water, which I believe remedies the hot spotting/burning. I think @jda is correct about most leds at higher par burning acros because most led users mount them much closer to the water, which produces a spot light hot spot.