LED par versus T5/MH

[Reef and Dive]

Have you noticed a difference in light results over corals in the same PAR for LEDs versus other illumination?

I have a mixed 65gal and have focused on SPS over the last 6 months.

I have 1 hydra 64 and 2 AI primes (that sit on the non-SPS side. Alk 8. Nitrate 2.8. Phos 0.03.
Moderate to strong flow with MP40 and glamorca on the other side.

Tank is 18in tall and lights 8in above water.
Using BRS configuration.
I have previously tried to distribute my PAR getting 250-400 on the SPS side.
To achieve that I have raised light intensity very slowly over months.

While I’ve been raising my PAR I actually noticed important worsening of many SPS, with clear burns of the top (light) side and totally stopped growing, even bleached some.

While it seemed my PAR was not tremendously high, something made me think:
My light curve to obtain this PAR have got 2 times more intense at least than most AI Signature series (and some like Saxby are over a really tall tank).

This made me think: those signature series of successful tanks were actually spreading a much lower par than mine. It was “as if” people with good presets are not measuring PAR at all or “PAR people” are not using LEDs to light the tank...

This made me go back to much lower PAR (Saxby reduced to around 60%) and many SPS are now recovering from this light “burn”. Stopped losing corals after that change and alk consumption doubled over a month after the change...

My question is, have you had similar experiences? It seems I was not having any success while being too worried about PAR numbers with these LEDs, and things are getting much better taking care of what my corals are telling me despite any PAR measurement over them.

Tank picture for reference:

Bleached SPS:

 

[Ron Reefman]

You talk about raising and lowering the PAR. How about some specifics?

 

[jda]

You cannot use as high of PAR from a LED as you can from T5 or MH. I would stay at 350 or below. Some can go higher depending on fixture height, longer acclimation times and stuff, but they are not the norm.

There are a lot of theories why, but what you are seeing is pretty normal. It is a light quality thing, one way or another. This is not usually a huge deal since most corals don't need much more. It is more of an issue trying to light larger areas with more power where the corals in the higher output areas can suffer.

 

[Reef and Dive]

You talk about raising and lowering the PAR. How about some specifics?

Raising to 250 at the bottom of the SPS platform, no good results, max 400.

Lowering to 150 max 280, corals much better.

 

[Nano sapiens]

Have you noticed a difference in light results over corals in the same PAR for LEDs versus other illumination?

The answer is 'yes' and the explanation is that LEDs typically have more PUR (photosynthetically usable radiation) than T5s or MHs at the same measured PAR. Since we can't really measure PUR, we're doing our best with PAR readings.

You can think of LEDs as having more of the 'blue spectrum' which promotes photosynthesis in corals, whereas T5 and MH also have spikes in green and other hues that don't add much to PUR, but add a lot to PAR.

 

[jwshiver]

When I switched from MH to Radion G5's I matched the G5 PAR to the MH PAR of upper 400's to low 500's in the highest point of the tank. I figured if that is the PAR they were use to it would make sense to keep it the same. I expected a small set back due to the change in spectrum but nothing major. BIG MISTAKE!
Within two days I woke up to a large portion of burned SPS. Needless to say I was sick to my stomach. I immediately reduced PAR by 50%. The damage continued to get worse for a few days before it stopped. I lost about 90% of my 2 year old Orange Passion colony and about 30% of some other multi-year old colonies. I slowly ramped up the PAR over a few weeks to the upper 300's at the highest point of the tank and all is well.

 

[Reef and Dive]

When I switched from MH to Radion G5's I matched the G5 PAR to the MH PAR of upper 400's to low 500's in the highest point of the tank. I figured if that is the PAR they were use to it would make sense to keep it the same. I expected a small set back due to the change in spectrum but nothing major. BIG MISTAKE!
Within two days I woke up to a large portion of burned SPS. Needless to say I was sick to my stomach. I immediately reduced PAR by 50%. The damage continued to get worse for a few days before it stopped. I lost about 90% of my 2 year old Orange Passion colony and about 30% of some other multi-year old colonies. I slowly ramped up the PAR over a few weeks to the upper 300's at the highest point of the tank and all is well.

That’s exactly my point!!! Lost corals because of this too!

 

[Reef and Dive]

@Dana Riddle have you noticed this on your studies?

 

[X-37B]

Most of my friends that run g4's and now g5's, or Orphek, run them at 50% and 24" off the tank to start.
They then slowly ramp up intensity at 24".
The led light is much more focused than say my MH.
Just my thought from what my friends experience on their tanks.

 

[Dana Riddle]

@Dana Riddle have you noticed this on your studies?

The Iwasaki 400-watt 'daylight' 6500K metal halide has been touted to be the best lamp ever for growing corals. I checked the PUR of it and it is 58%. PUR of a LED lamp (off the scale Kelvin wise, but probably 12000-14000K) was 72%. So, I'm not surprised that matching PAR of different light sources could cause some problems.

 

[Reef and Dive]

The Iwasaki 400-watt 'daylight' 6500K metal halide has been touted to be the best lamp ever for growing corals. I checked the PUR of it and it is 58%. PUR of a LED lamp (off the scale Kelvin wise, but probably 12000-14000K) was 72%. So, I'm not surprised that matching PAR of different light sources could cause some problems.

Thanks for the answer Dana!

 

[blasterman]

Always go by your corals when it comes to PAR.

Yes, actual PAR can vary with different light sources given t5, halide and LEDs differ so greatly in their light emissions. Plus, LEDs typically have optics and a tiny foot print.

Suggestions: turn off the stupid UV channels on those lights. Why in the world do you want to have light in a wavelength you can barely see but contribute PAR? So your tank is darker and more purple but corals more bleached?

 

[A. grandis]

Have you noticed a difference in light results over corals in the same PAR for LEDs versus other illumination?

I have a mixed 65gal and have focused on SPS over the last 6 months.

I have 1 hydra 64 and 2 AI primes (that sit on the non-SPS side. Alk 8. Nitrate 2.8. Phos 0.03.
Moderate to strong flow with MP40 and glamorca on the other side.

Tank is 18in tall and lights 8in above water.
Using BRS configuration.
I have previously tried to distribute my PAR getting 250-400 on the SPS side.
To achieve that I have raised light intensity very slowly over months.

While I’ve been raising my PAR I actually noticed important worsening of many SPS, with clear burns of the top (light) side and totally stopped growing, even bleached some.

While it seemed my PAR was not tremendously high, something made me think:
My light curve to obtain this PAR have got 2 times more intense at least than most AI Signature series (and some like Saxby are over a really tall tank).

This made me think: those signature series of successful tanks were actually spreading a much lower par than mine. It was “as if” people with good presets are not measuring PAR at all or “PAR people” are not using LEDs to light the tank...

This made me go back to much lower PAR (Saxby reduced to around 60%) and many SPS are now recovering from this light “burn”. Stopped losing corals after that change and alk consumption doubled over a month after the change...

My question is, have you had similar experiences? It seems I was not having any success while being too worried about PAR numbers with these LEDs, and things are getting much better taking care of what my corals are telling me despite any PAR measurement over them.

Tank picture for reference:

Bleached SPS:

Many people get caught on the PAR numbers alone and completely forget about other things. Observing your system is the best you can do to decide what they need in many ways. Number are great to guide you, but when the corals are doing fine you should respect and appreciate the results.
The differences between LEDs, halides and/or T5s is the way the photons are produced, distributed and delivered to the corals.
"Photons are photons", but different types of lights will have their limitations in regards to what photons are produced, blended and delivered. That is huge!
What meters can read is also limited to what they were made to detect.
Many have reported the best results using LEDs are from fixtures trying to mimic T5s. Those fixtures will deliver light in a more distributed manner.
No one really knows what is the full explanation for what you experienced there, specially comparing them to other sources of light, but many have suffered as well. Just keep the lower PAR and they will get better. Those are the limitations when using most LEDs.
I hope that helps.

 

[Reef and Dive]

Many people get caught on the PAR numbers alone and completely forget about other things. Observing your system is the best you can do to decide what they need in many ways. Number are great to guide you, but when the corals are doing fine you should respect and appreciate the results.
The differences between LEDs, halides and/or T5s is the way the photons are produced, distributed and delivered to the corals.
"Photons are photons", but different types of lights will have their limitations in regards to what photons are produced, blended and delivered. That is huge!
What meters can read is also limited to what they were made to detect.
Many have reported the best results using LEDs are from fixtures trying to mimic T5s. Those fixtures will deliver light in a more distributed manner.
No one really knows what is the full explanation for what you experienced there, specially comparing them to other sources of light, but many have suffered as well. Just keep the lower PAR and they will get better. Those are the limitations when using most LEDs.
I hope that helps.

Exactly. Now I’m following my corals, not my PAR. I will also add diffusers like my experienced friend @junio melo did with better success.

 

[A. grandis]

Exactly. Now I’m following my corals, not my PAR. I will also add diffusers like my experienced friend @junio melo did with better success.

With the use of diffusers you will loose some PAR, than you can increase the intensity a bit to compensate. Measure PAR before and after you add the diffuser and you will see how much that particular diffuser will decrease PAR over your tank after installation. If you want to keep the same PAR you have now, you will most likely have to measure PAR it in order to correct. The percentage of PAR lost after you install a diffuser will depend basically on how opaque and the thickness of the material you will utilize. Keep in mind that the distance between the fixture, the diffuser, and the corals will have to come to a balance in order to optimize the spread your diffuser will allow. All that needs to be adjusted with the intensity and PAR measured to assure the best result using a diffuser. I assume you will make your own diffuser. Each fixture will react differently to those distances and material(s) used. Besides, the position (distance and angle) of each fixture will play it's own part. It's important to keep the fixture cool, so I would avoid getting the diffuser too close to the diodes.
Good luck!

 

[Reef and Dive]

With the use of diffusers you will loose some PAR, than you can increase the intensity a bit to compensate. Measure PAR before and after you add the diffuser and you will see how much that particular diffuser will decrease PAR over your tank after installation. If you want to keep the same PAR you have now, you will most likely have to measure PAR it in order to correct. The percentage of PAR lost after you install a diffuser will depend basically on how opaque and the thickness of the material you will utilize. Keep in mind that the distance between the fixture, the diffuser, and the corals will have to come to a balance in order to optimize the spread your diffuser will allow. All that needs to be adjusted with the intensity and PAR measured to assure the best result using a diffuser. I assume you will make your own diffuser. Each fixture will react differently to those distances and material(s) used. Besides, the position (distance and angle) of each fixture will play it's own part. It's important to keep the fixture cool, so I would avoid getting the diffuser too close to the diodes.
Good luck!

Great and thanks. Will do that. Diffuser arrives this week. I will give an update later on after some extra weeks.