Leds and par readings?

[Mr. D]

Can someone chime in and give a good strategy for reading close to accurate par under leds?

I have heard how blues need to be compensated by 20 percent from what is read, but if you have a mix of white and blue the par meter should read fairly accurately.

I run an arctic model from ocean revive. Really well built light and I enjoy it a lot, but I notice my Zoas have more trouble acclimating to the leds than anything else, sps and lps alike.

Thanks for suggestions!

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[ReefLEDLights]

Here is a link that may help

http://www.apogeeinstruments.com/aquarium-par-meters/

Shooting from the hip a 2:1 Blue:White is about 12-17% less than advertised...



Bill

 

[Ron Reefman]

I agree with Bill about the link to Apogee. But I'd say it reads about 8-12% low. Hardly enough to worry about. The PAR meters are very touchy and the reading can change 10-20% just by tipping the sensor a small amout or moving up or down a fraction of an inch.

I have Arctic S026 over my 10" deep frag tank and my 20" deep 55g tank. I run them at 50% white and 75% blue and my zoos do just fine.
Hope that helps.

 

[Mr. D]

What kind of acclimation procedure did you go through?

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[Mr. D]

Bump

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[CoryC]

We spoke about this the other day I think, but I think zoas are probably the least sensitive of the corals you have to LEDs. Mine are under a variety of light and flow intensities in my tank and all do well. Have you tried a different light source to see if they open fully? How are you acclimating the zoas currently?

 

[flowflezy]

Since I switched to leds my zoas love it and look amazing. They are fully opened up and have babies everywhere now..

 

[Mr. D]

I went from t5s to the leds. Once I put the leds over the tank I had to shade some Zoas to keep them happy until they acclimated. I have used a par meter and made sure my number were close to what I had under t5s but had to bump up a bit since my tank is deeper. Currently I have my whites at about 15 percent and blues at about 60-70 percent. I run an aquamaxx hob skimmer, bag of carbon, and just recently put a very small amount of gfo in. Maybe an 1/8th of a cup.

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[Mr. D]

Some Zoas and palys look just fine, others seem to not be doing do hot with the new lights. Oddly enough my chalices love the leds the most.

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[ReefLEDLights]

My Chalices did better after switching to LEDs. They are a bit lower with a PAR around 200-250.

Surprisingly My hammers which can be a low to medium light coral grew better under the LEDs around 400-450 PAR. One was the diameter of a 5 gal salt bucket before it got donated to the Shedd.

If you do have a PAR mater to reference before and after I would start 30% below your original lights then ramp up 5% per week. During this period feed the corals.

Bill

 

[Mr. D]

Ok, I may try that. Currently I have the leds set close to what I previously had, but cut back the photoperiod to 4-5 hours instead of 8.

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[ReefLEDLights]

LEDs or at least ours are spectrum specific. "Chosen to generate more photosynthetic activity"...

Sounds like a good add, but anything in the 420-460nm range will be brighter than advertised...

Bill

 

[ReefLEDLights]

Forgot to mention this intensity curve replicates the natural intensity on the coral reef...

Dimmable Drivers and a good controller can do this.

From the Modern Coral Reef Aquarium Vol 1 by Fossa and Nilsen

Bill

 

[Mr. D]

I failed to mention, I already do feed my corals at least once a week. I measured par today. I'm getting about 300 roughly 18'' away (top most coral placement), 170-200 mid level and 130-150 sand bed.

Is decreasing photoperiod a good option, or is it suggested I estimate light output to more than what is measured and dim a bit and start the 5 percent a week regimen?

I probably need to cut the blues back I'd say.

Thanks for everyone's input.


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[Ron Reefman]

Cutting the photo period is not the same as reducing the total PAR. I switched my leds from a 4hr sunrise, 5 hr midday at 90% blue & 40% white, and a 5hr sunset (after 6 months) to a new program of an 8hr sunrise and 8hr sunset with just 1hr at 100% on both. In 3 days I was starting to bleach 1 high placed coral. So I dialed it back to peak at 90% blue and 70% white and after 2 weeks everything is stable.

If you have a PAR meter, test the PAR of your blue and white channels separately. I found my OceanRevive Arctic S026 had a blue PAR that is roughly 30% more than the white PAR. And I think the Apogee meter is about equally low on both? It's a bit low over a range of 400nm to 450nm (roughly) and it's OK at the red end up to 650nm or so and then falls off a cliff. But how much of a white led's spectrum is up that high? I suspect it's not much.

Also, you'll find the separate blue and white PAR values are just added together, i.e. if you read the PAR of both together it's the same as when you add the 2 separate values.
Example: Blue PAR of 600 + white PAR of 400 = total PAR of 1000, then test total PAR and it will be 1000 (+or- a small error rate).

 

[Mr. D]

Thanks for the info. I have since dialed back the percentages and will keep them there a week.

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[kacrocorals581]

What kind of led are you running Mr.D

 

[Mr. D]

Ocean revive arctic model

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[Ron Reefman]

Just in case you are interested, I have 2 of them over a 55g with corals only at the bottom (it's a QT more than anything) and I run at 75% blue and 50% white.

 

[Mr. D]

I have switched to probably 10 percent white and about 50 percent blues.

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