Consensus on PAR Values?

[Buzz1329]

I can't seem to find anything approaching a consensus of the appropriate PAR values for SPS coral (e.g., aocropora, montipora, pavnoa, pocilopora, porites, stylophora, etc.). Numbers I see recommended generally range from 100 to 500 with a few outliers insisting that those are minimal light requirements and we should generally be shooting for PAR values in the 600-1,000 range.

I have ordered an Apogee PAR meter and will be testing the PAR values in my tanks under MH/T5 fixtures vs. LED fixtures. But now I'm wondering what the point is. If, as some say, there are SPS species such as Acropora, Montipora, and Pavona, that do very well indeed at PAR values in the 100s "“ maybe I should go back to NO fluorescents.

Or maybe I should conduct tests of how particular species fare under different PAR readings generated by different types of lighting? But this too seems like it won't be of much help as I see that micro-environments (even within the same tank) can have dramatic effects on PAR readings.

So is the take away from this that SPS coral have very adaptable lighting needs and that provided there are other needs are met, can thrive under a variety of different PAR levels, provided they are carefully acclimated to a new lighting regime?

If that's the case, it would seem to support replacing cumbersome, energy hog MH fixtures with lower PA and higher energy-efficiency LED lights.

Thanks,

Mike

 

[Volcano1]

Pretty good link with some good arguments for Par values.I think the high spot in my tank is the 500 range. HTH's
http://reefcentral.com/forums/showthread.php?t=1963431&page=3

 

[jda]

IMO, PAR is second in importance to spectrum.

Honestly, I don't think that anybody knows what each coral wants. There are some lower end "need" numbers around, like posted above, that will keep them alive and doing OK. We have all seen coral respond differently with both lower and higher light. I kept coral in a tank outside in Missouri at the par was well over 1200 most of the time and over 1500 during the middle of the day and all of the SPS thrived and grew like crazy. I believe that there is no such thing as too much good light, but do believe that there is such a thing as too much bad light. So, the amount of PAR that a coral can handle is based on the amount of bad light that comes from the source. For MH, this is probably up to 1000 PAR, if you can get there. For T5, probably 1000 too. For LED with excess white spectrum (red/yellow/green), maybe 200-300 - this is why you see so many old fixtures with the whites turned way down, and also so many new fixtures with very few whites included.

I would think about PAR after spectrum is right.

I use 250W HQI 14K Phoneix bulbs - 3 over a standard 120G. Each apogee is different and can be off by some factor, but like 10" deep, I am at about 425 with values about 200 in the sand in the middle and 150 on the edges. There are times when I put a second AquaMedic pendant over my tank and double up the lights - you can just about double those PAR values when this happens. The upper branches of some tort and stags that are near the top see over 1000 with both lights on there.

 

[Peter Eichler]

I think it varies dependng on light source. Lower values with T5's can produce similar results to higher par levels with metal halides. In my experience 200-600 par with MH's is a good place to be for most high light acroporas cand most other SPS. The sweet spot depends on the particular coral. If you manage to get 500 or 600 par with MH's and there's a good chance you're bleaching some corals. LED's are probably more similar to MH's.