Been frying my corals because of this!

[Centerline]

I don't use a par meter, but have used a lux meter using the conversion math that @saltyfilmfolks provided some time ago.

With that said, I set my light intensity to @Dana Riddle's 2016 macna presentation. His findings have been spot on in my system. 200-250 par does seem to be the sweet spot for my SPS. Lots of flow and 8-9 dkh with N03 between 5-10ppm and P04 below .02.

@revhtree, what was your par before and now after?

What is your light schedule like?

 

[Flippers4pups]

What is your light schedule like?

9 hours blue, 7 hours white.

 

[Servillius]

I’m going a bit off topic and dredging up this thread again because I think @Dana Riddle had said something about wanting data.

About a few months ago I decided to try 250w Giesseman Bulbs. I didn’t hate the look, but I finally got around to testing and my corals were getting about 225 near the top and 150 PAR at the lower colonies.

I switched back to 400w and am driving them on the highest setting on my select-a-watt through very clear water. I tested at over 500 Par on the highest corals and 400ish PAR for the majority of my colonies. I’ve made no other significant changes in the last month. The growth tips are noticeably longer and have been for the last two weeks and everything is growing faster than it has been as well as being more colorful.

First a crappy pic to show some of my highest placed corals in relation to the bulbs some 8” above the water.

Then a few FTS to get an idea of general health.

I’m not even close to suggesting this refutes any of your findings. My evidence is hardly scientific and if it was it’s a single data point.

I do believe there is more to the story of PAR. Some possible considerations include how branching is related to all this (for instance do acro branch as a high light strategy in order to shade some of the colony; does this mean a larger colony is happier in higher par even though the most exposed parts are not?), how does the LED story relate to this (when there is more indirect light corals may be happier dealing with some high par spots), or perhaps they’re just willing to crowd out competitors rather than limit themselves to ideal spaces and wait to be crowded out themselves.

Here’s a comparison of growth tips on my blue stag before and after. Note the number of new tips in the lower, higher light pics. That’s a week old and there are even more now.

Thank you for all the hard work reducing this to real knowledge. I hope I’m offering something useful in the analysis.

 

[Cory]

I disagree that it invalidates the point, unless you are suggesting that desiccation, UV, temperature are a benefit to overcome the supposed detriment of the high PPFD. Why else would a Chinese Black Box with white diodes up too high fry coral out of existence in nearly perfect conditions at 350-400 PAR when a supposed over saturation of sunlight cannot harm them in these harsh conditions where they should be weaker to begin with. What would those be getting, about 2000 to 2200 PPFD? If so, then this is 6-8x more than what is supposed in some papers. Surely if over saturation of high quality was indeed a detriment, then the other harsh conditions such as UV, temp, etc. would finish them off faster, not be so hardy that they can overcome and thrive.

I believe that this illustrates the point like other that spectrum and quality does matter. Reverse the logic... if we give less harsh environment than this, why will coral burn and die with 1/6 of the quantity of some types of light?

I wonder if coral slime would significantly protect them from being exposed to the sun at low tide?