Metal Halide vs. LED Rates of Photosynthesis

[Dana Riddle]

I was looking through some PowerPoint presentations for a particular slide and found this. Frankly, it was so long that I had forgotten that I even did the experiment - Iwasaki MH rate of photosynthesis versus that of blue/white LEDs. This was determined using a Li-Cor PAR meter and a Walz PAM fluorometer.

 

[BeltedCoyote]

Bad day to still be glasses-less.

I’m by no means an expert on this matter.
however, I’d im reading the data correctly it appears you found negligible differences between both fixtures.

am I interpreting this correctly?

 

[Dana Riddle]

Bad day to still be glasses-less.

I’m by no means an expert on this matter.
however, I’d im reading the data correctly it appears you found negligible differences between both fixtures.

am I interpreting this correctly?

At lower light intensity (up to about 200 PPFD), there is very little difference. Greater than 400, the differences are huge.

 

[BeltedCoyote]

At lower light intensity (up to about 200 PPFD), there is very little difference. Greater than 400, the differences are huge.

ah okay. Looking again I see I did misinterpret the data.

without derailing this too much. How does t5 fall if compared at similar intensities? If you would rather field this question via pm or link a thread/article I missed please feel free!

 

[Dana Riddle]

I haven't compared

ah okay. Looking again I see I did misinterpret the data.

without derailing this too much. How does t5 fall if compared at similar intensities? If you would rather field this question via pm or link a thread/article I missed please feel free!

I haven't compared T5s to any other light source. Setting up one of these procedures is usually a 9-hour day.

 

[Brymac1]

Was this part of a larger study? If so, would you mind sharing?

 

[Acros]

Is it pretty much saying that LEDs are equally as good at lower par and better at higher par?

 

[CayeCaulker]

So what I am gathering from this information is LPS / Mixed LED will work. For dominated SPS looks like Metal Halide is King.

For me, the actual look to my eye is equally important. I scuba dive and I know what the reef looks like in person. I want that look. I am not very fond of all this disco tech black light blue and shadows. I see reef tanks under black lights and fluorescent shrooms and I just want to puke. It gives me a headache just walking into some fish shops. Unless I want to spend a fortune on LED lighting and have fixtures all over I can't get the spread I want and the shimmer I love on the top reef.

I got some Hamilton Pendants and T5's 14k metal halide and it looks amazing. It's proven, simple, and effective. Granted my tank is new and the lights are off right now but I ran the exact same system 15 years ago with the exact same lights and grew SPS like crazy. I had to cut them back as they fought for real estate. I wanted to go LED but I just couldn't do it. I wanted power savings, Heat savings, no relamping and control over sunrise and sunset. I wanted everything LED offered me. But in the end... I didn't like how it looked. I couldn't do it. I couldn't give up that look. I love everything about LED except how it looks.

I am always open to new ideas and systems. I hope one day I can have my cake and eat it too. I hope someday I like how LED looks!

 

[hart24601]

So what I am gathering from this information is LPS / Mixed LED will work. For dominated SPS looks like Metal Halide is King.

For me, the actual look to my eye is equally important. I scuba dive and I know what the reef looks like in person. I want that look. I am not very fond of all this disco tech black light blue and shadows. I see reef tanks under black lights and fluorescent shrooms and I just want to puke. It gives me a headache just walking into some fish shops. Unless I want to spend a fortune on LED lighting and have fixtures all over I can't get the spread I want and the shimmer I love on the top reef.

I got some Hamilton Pendants and T5's 14k metal halide and it looks amazing. It's proven, simple, and effective. Granted my tank is new and the lights are off right now but I ran the exact same system 15 years ago with the exact same lights and grew SPS like crazy. I had to cut them back as they fought for real estate. I wanted to go LED but I just couldn't do it. I wanted power savings, Heat savings, no relamping and control over sunrise and sunset. I wanted everything LED offered me. But in the end... I didn't like how it looked. I couldn't do it. I couldn't give up that look. I love everything about LED except how it looks.

I am always open to new ideas and systems. I hope one day I can have my cake and eat it too. I hope someday I like how LED looks!

Out of curiosity how did that graph lead you to this conclusion that for sps MH is king? I get it if you like the look, that’s a great reason to run it. But I don’t see that reflected here.

 

[xiaoxiy]

So what I am gathering from this information is LPS / Mixed LED will work. For dominated SPS looks like Metal Halide is King.

For me, the actual look to my eye is equally important. I scuba dive and I know what the reef looks like in person. I want that look. I am not very fond of all this disco tech black light blue and shadows. I see reef tanks under black lights and fluorescent shrooms and I just want to puke. It gives me a headache just walking into some fish shops. Unless I want to spend a fortune on LED lighting and have fixtures all over I can't get the spread I want and the shimmer I love on the top reef.

I got some Hamilton Pendants and T5's 14k metal halide and it looks amazing. It's proven, simple, and effective. Granted my tank is new and the lights are off right now but I ran the exact same system 15 years ago with the exact same lights and grew SPS like crazy. I had to cut them back as they fought for real estate. I wanted to go LED but I just couldn't do it. I wanted power savings, Heat savings, no relamping and control over sunrise and sunset. I wanted everything LED offered me. But in the end... I didn't like how it looked. I couldn't do it. I couldn't give up that look. I love everything about LED except how it looks.

I am always open to new ideas and systems. I hope one day I can have my cake and eat it too. I hope someday I like how LED looks!

I see the exact opposite of your conclusion from this graph.

rETR is relative electron transport rate, which increases with higher levels of photosynthesis. The graph shows that for Pocillopora, at lower PAR levels (<200 PAR) LEDS and Halides have similar rates of photosynthesis. At higher PAR levels (>200 PAR) LEDs had higher photosynthesis than Halides.

 

[BeltedCoyote]

I haven't compared

I haven't compared T5s to any other light source. Setting up one of these procedures is usually a 9-hour day.

makes sense. Question stemmed from curiosity only.

 

[Spare time]

Do you think this has to do with the more limited spectrum of using only blue and white LED's, and that certain aspects of the zooxanthellae photosystem are getting overwhelmed (compared to the same par but spread out over different wavelengths)? I would think that to be a flaw in the study as yes the par is the same but it's not the same color of light being given out by the sources.

 

[CayeCaulker]

I see the exact opposite of your conclusion from this graph.

rETR is relative electron transport rate, which increases with higher levels of photosynthesis. The graph shows that for Pocillopora, at lower PAR levels (<200 PAR) LEDS and Halides have similar rates of photosynthesis. At higher PAR levels (>200 PAR) LEDs had higher photosynthesis than Halides.

I think you are right and I misread that.

That's really interesting.

 

[Bpb]

Results are quite surprising. I’d love to hear the continued discourse on the topic

 

[CayeCaulker]

Me too! I would like to see growth measured. Much of the info we digest is often colored by opinion, not science. I like metal halides because of how they look. but I am open to learning that's for sure.

 

[Acrofiend]

This should put a lot of “metal halide are best” threads to rest.
Although I wonder if a 20k radium would compete with the LED’s.

 

[ATXreefer]

@Dana Riddle do you by chance have the spectrum data of LED and halide lamp used in this experiment. Would love to see what that looks like and if any conclusions can be drawn from that.

 

[HudsonReefer2.0]

So what I am gathering from this information is LPS / Mixed LED will work. For dominated SPS looks like Metal Halide is King.

For me, the actual look to my eye is equally important. I scuba dive and I know what the reef looks like in person. I want that look. I am not very fond of all this disco tech black light blue and shadows. I see reef tanks under black lights and fluorescent shrooms and I just want to puke. It gives me a headache just walking into some fish shops. Unless I want to spend a fortune on LED lighting and have fixtures all over I can't get the spread I want and the shimmer I love on the top reef.

I got some Hamilton Pendants and T5's 14k metal halide and it looks amazing. It's proven, simple, and effective. Granted my tank is new and the lights are off right now but I ran the exact same system 15 years ago with the exact same lights and grew SPS like crazy. I had to cut them back as they fought for real estate. I wanted to go LED but I just couldn't do it. I wanted power savings, Heat savings, no relamping and control over sunrise and sunset. I wanted everything LED offered me. But in the end... I didn't like how it looked. I couldn't do it. I couldn't give up that look. I love everything about LED except how it looks.

I am always open to new ideas and systems. I hope one day I can have my cake and eat it too. I hope someday I like how LED looks!

I don’t think that’s what’s represented.

 

[ATXreefer]

This should put a lot of “metal halide are best” threads to rest.
Although I wonder if a 20k radium would compete with the LED’s.

Your logic of having more comparable spectrums between the two light sources producing more similar results makes sense to me. That being said, I often read that iwasaki 6500k was the best at growing sps the fastest (though I’ve never seen empirical data) and that seems counterintuitive to me given what we know about photosynthetic absorption ranges being strongest in the blue zone. I’ve been researching aquarium lighting for a couple years now and still can’t make sense of it at times.

 

[J1a]

100 umol/m2/s of 420nm radiation will be exactly that, regardless if it comes from a MH, T5 or a LED.

Perhaps as a hobby we are at the point where we should start to look beyond the light sets, and focus on the spectral intensity.

Which wavelengths is more prone to triggering photosaturation? Which other wavelengths could potentially mitigate the effect? I think answering such questions, with data, can have profound impact on how reefer make choices about lights.