Acclimating corals in general to higher PAR

kartrsu

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I used to think that acclimation to higher light intensity and PAR for SPS, LPS, softies is successful if the rate of change is slow. I have some torches that I can’t get past 150 PAR without less polyp extension. I’m wondering if it’s not as simple as cranking up the lights slowly (I was increasing by 1% a day, maybe that is too fast?). Is there something else that needs to be managed hand in hand with increasing light intensity such as higher nutrients, higher alk, temp? Side note, but I’m dialing up light intensity to bring out coloration of my torches.
 

Nano sapiens

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I used to think that acclimation to higher light intensity and PAR for SPS, LPS, softies is successful if the rate of change is slow. I have some torches that I can’t get past 150 PAR without less polyp extension. I’m wondering if it’s not as simple as cranking up the lights slowly (I was increasing by 1% a day, maybe that is too fast?). Is there something else that needs to be managed hand in hand with increasing light intensity such as higher nutrients, higher alk, temp? Side note, but I’m dialing up light intensity to bring out coloration of my torches.

Yes, slow is much better than too fast. Typically, 5%/week has been used by many with good results, so you are in the ballpark.

IME, pushing corals lightwise to obtain ever more intense coloration carries with it risk. There comes a point (dependent on coral type) where 'more is not better' and pushing past this light saturation point can cause severe damage since the coral may not be able to sufficiently detoxify the accumulating oxygen free radicals (ex: hydrogen peroxide).

The generally accepted upper range for many LPS is ~150 PAR. Some can take a bit more without serious consequences, but many also prefer less. The better policy IMO is to provide sufficient light that doesn't overly stress the coral and work on providing reef correct and stable water parameters along with sufficient high quality foods to encourage the development of pigmentation.
 
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kartrsu

kartrsu

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Yes, slow is much better than too fast. Typically, 5%/week has been used by many with good results, so you are in the ballpark.

IME, pushing corals lightwise to obtain ever more intense coloration carries with it risk. There comes a point (dependent on coral type) where 'more is not better' and pushing past this light saturation point can cause severe damage since the coral may not be able to sufficiently detoxify the accumulating oxygen free radicals (ex: hydrogen peroxide).

The generally accepted upper range for many LPS is ~150 PAR. Some can take a bit more without serious consequences, but many also prefer less. The better policy IMO is to provide sufficient light that doesn't overly stress the coral and work on providing reef correct and stable water parameters along with sufficient high quality foods to encourage the development of pigmentation.
Thanks! I just took out my Seneye PAR meter and measured light intensity at peak photoperiod. Seems like most of my torches are actually around 150-200 range, so higher than I presumed. Often times when I ask vendors what light intensity their torches are under, I usually get a response in the 200-300 range.

All in all, I agree with you that providing sufficient light should be the starting point. So does this mean that tolerance of higher light intensity has nothing to do with any water parameter and is more about ability to detoxify free radicals fast enough? I was wondering if there was a relationship similar to how higher alk and low nutrients with SPS causes alk burn.
 

Nano sapiens

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Thanks! I just took out my Seneye PAR meter and measured light intensity at peak photoperiod. Seems like most of my torches are actually around 150-200 range, so higher than I presumed. Often times when I ask vendors what light intensity their torches are under, I usually get a response in the 200-300 range.

All in all, I agree with you that providing sufficient light should be the starting point. So does this mean that tolerance of higher light intensity has nothing to do with any water parameter and is more about ability to detoxify free radicals fast enough? I was wondering if there was a relationship similar to how higher alk and low nutrients with SPS causes alk burn.

Higher PAR is possible when PUR is lower, but typical LEDs put out a lot of PUR. I used to keep Euphyllia (including Torches) under PCs and T12s and coral color was quite good for the day. In those days we had no PAR meters and PUR was likely lower due to more 'white' light vs blue (unlike today's bluer light LEDs), but I suspect ~80 - 120 PAR.

Keeping Torches in 300 PAR (LEDs) seems to me to be dangerous and may be past their light saturation point as they typically come from mid depth and/or shallower/turbid water conditions (very high photosynthesis rates is what can cause excessive oxygen free radicals). If the coral's methods to deal with these radicals is overtaxed, they 'burn up' from the inside out. Naturally, since big money is involved with Torches these days, some vendors might be tempted to push corals to develop super intense coloration and thereby increase the likelihood of a sale (and the price!). But the real danger is that the person receiving such a coral may have 'damaged goods' that aren't readily apparent, but can become apparent a week or three after being received.

I can't say if you can infer that the theory regarding SPS and high alkalinity/low nutrients causing 'alk burn' can be applied in any meaningful way to LPS like Euphylia, but here is an interesting study regarding water parameters with references to photosynthesis:

https://reefs.com/magazine/the-effect-of-ph-alkalinity-and-calcium-on-hermatypic-corals/
 
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