PAR values under my DIY LED

skurious · Mar 9, 2013

m2434 said: ↑

This is a myth perpetuated by Apogee, probably because they are a company that has absolutely no experience with reef aquariums. I have discussed the issue with them and their comparisons are based on a 5500K metal halide (because of course that is what all of us are using : ).

The the more blue you go, the more the apogee will underestimate, this is regardless of lighting type. A lot of halides actually have more deeper blue than a lot of LEDs though, as royal blue does not go much below 450nm for example and a lot of halides have spikes around 420. Also, LEDs don't have tons of red, some halides do and the Apogee also underestimates red, not just blue. So, in many cases you could actually find that the halide is more underestimated.

As to the PAR numbers, it depends more on optics and total system wattage, which you don't display. Technically, halides should still output more total visible light (PAR x area), but may not focus as well (visible light / area=PAR). So, if your using wide optics, or significantly less wattage than an halide necessary to cover the tank, you could get less PAR for sure. Mostly the reason to run LEDs at lower PAR, in my experience, is to acclimate corals to the change in spectral characteristics. We used to do the same with halides when switching from say a 10K to a 20K, it could take a long time for corals to adapt. However, they can adapt, in my Fluval edge, I have zoanthids, Ricordia, other mushroom corals , leathers etc... Under over 400-600PAR (per Apogee meter) of LED lighting, for IIRC nearly 2 years and they seem to love it....
Click to expand...

Well that makes quite a bit more sense than what ive read where people are saying "apogee under estimates blue leds".

thank you for the information.

exactlyobp · Mar 9, 2013

skurious said: ↑

I've read that the par meters usually read LED lower, primarily the blue leds. YOu have your Royal blues at 100% so if thats the case then your par is probably quite a bit higher than what the meter is showing. I cant remember what number I read, but I swear it was over 10%, and closer to 30%.
Click to expand...

m2434 said: ↑

This is a myth perpetuated by Apogee, probably because they are a company that has absolutely no experience with reef aquariums. I have discussed the issue with them and their comparisons are based on a 5500K metal halide (because of course that is what all of us are using : ).

The the more blue you go, the more the apogee will underestimate, this is regardless of lighting type. A lot of halides actually have more deeper blue than a lot of LEDs though, as royal blue does not go much below 450nm for example and a lot of halides have spikes around 420. Also, LEDs don't have tons of red, some halides do and the Apogee also underestimates red, not just blue. So, in many cases you could actually find that the halide is more underestimated.

As to the PAR numbers, it depends more on optics and total system wattage, which you don't display. Technically, halides should still output more total visible light (PAR x area), but may not focus as well (visible light / area=PAR). So, if your using wide optics, or significantly less wattage than an halide necessary to cover the tank, you could get less PAR for sure. Mostly the reason to run LEDs at lower PAR, in my experience, is to acclimate corals to the change in spectral characteristics. We used to do the same with halides when switching from say a 10K to a 20K, it could take a long time for corals to adapt. However, they can adapt, in my Fluval edge, I have zoanthids, Ricordia, other mushroom corals , leathers etc... Under over 400-600PAR (per Apogee meter) of LED lighting, for IIRC nearly 2 years and they seem to love it....
Click to expand...

Wow, thanks for the detailed info!! +k!!

bhazard · Mar 18, 2013

how many leds are you using? The number is very low.

Daniel072 · Mar 18, 2013

Honestly, I think something is screwing up your numbers. This is why I have never even thought about putting a par meter in my tank. My colors are good, growth is great, and I'm happy with the tank. Even if I were only getting 25 at the bottom, I would still be happy because my tank looks good. Your tank looks outstanding as well, regardless of the par.

exactlyobp · Mar 18, 2013

bhazard said: ↑

how many leds are you using? The number is very low.
Click to expand...

The fixture has 60 LEDs, mainly Cree XPs. This is my DIY LED thread, if you were interested.

Daniel072 said: ↑

Honestly, I think something is screwing up your numbers. This is why I have never even thought about putting a par meter in my tank. My colors are good, growth is great, and I'm happy with the tank. Even if I were only getting 25 at the bottom, I would still be happy because my tank looks good. Your tank looks outstanding as well, regardless of the par.
Click to expand...

I know, right Daniel? A trusted reefer guy tells me to dim it down, the other says not enough.. but my corals are growing, even tho i want them to ripen their colors, all the signs in there show that I have enough light..

Daniel072 · Mar 18, 2013

if you need to intensify, do it SLOWLY. My colors are really starting to come out after my bleach job and I dimmed my light. I went too agressive with gfo, carbon and lighting and now paying the price for it. LED's are way more intense than people give them credit for.

exactlyobp · Mar 18, 2013

Thanks for your input. When i had the manual pots for LED dimming, the wife wouldnt stop cranking them up when i was at work! Luckily, there was no ill effect on corals, but i was scared shi!tless. Of course i got the VDM soon after

My plan is to swap out some of existing LEDs with better ones and raise the fixture to get better spreads. Nothing drastic.

daido · Mar 24, 2013

you have some big differences between the top to the bottom reading. I think it is beacuse the beam angle of your leds is too wide. If you can, I recommand putting 80-90 degree lenses on about 75% of the leds and checking the par again.

hart24601 · Mar 24, 2013

Great article about LEDs and PAR meters.

Aquarium Equipment: PAR Meters and LEDs - How Accurate are the Measurements? A Comparison of Three Meters and Lux to PAR Conversion Factors for LEDs — Advanced Aquarist | Aquarist Magazine and Blog

hart24601 · Mar 24, 2013

Great article about LEDs and PAR meters.

Aquarium Equipment: PAR Meters and LEDs - How Accurate are the Measurements? A Comparison of Three Meters and Lux to PAR Conversion Factors for LEDs — Advanced Aquarist | Aquarist Magazine and Blog

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PAR values under my DIY LED

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PAR values under my DIY LED

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