OP
OP
tnyr5
Tony
I'm really puzzled on how you're getting away with these extremely high numbers. If you look at the research....specifically @Dana Riddle 's eloquent work that was presented at MACNA 2016....he showed that Rate of Photosynthesis (in Porites) maxes out at about 115 PAR:
And, once you get past 200 PAR or so, you start getting photoinhibition....slow down of coral growth.
His conclusion about light from this study was a PAR between 115-200 for maximum growth rates.
I've got to believe you're in full blown photoinhibition in your tank, similar to what Dana found mid-day in the shallow tidal pools.
If interested..... and I've linked this video so many times, I'm going to have to start paying royalties....here is the entire talk from Dana.
In part, because of this talk, I've increased flow in my tank (5 foot 90 gallon tank) by having four MP40's and one MP10...and considering adding one more MP10. In addition, I've turned my lights down. I used, what I call "the Poor man's PAR meter"....in fact, a LUX meter...that I purchased for less than $15. My corals grow like weeds! It is my opinion that this video should be mandatory viewing by all new reefers.
I'd be curious to hear about your coral growth after, let's say, three months.
This coral would be a brown turd at 200 par lol.
The Porites coral in those procedures was deliberately chosen since it could be cut into multiple plugs (frags) that offered a relatively flat surface for testing with the fluorometer. Secondly, it was the predominant coral in the tidepool was only inches deep - this would allow examination of how this coral species had adapted to an intense light field (likely as much as any coral would ever experience in Hawaii.) The results - this Porites coral had not adapted to intense light - it still reached photosaturation at a low value. The surfaces most exposed to sunlight were bleached and shaded areas contained the most chlorophyll. These fist-sized tidepool corals were stunted in growth when compared to deeper water corals (some 'deep' Porites are as big as a house.) Now, to look at other factors. The Porites in these procedures contained Clade C15 zooxanthellae. It is tolerant of high light and temperature - to a point of course! Some other clades are highly adaptable to light intensity - some very poorly so. A Hawaiian coral - Pocillopora molokensis - is a deep water species and would certainly die if placed in this tidepool (even if allowable to slowly adapt.) Another factor is branching - this offers a great deal of self-shading where some areas are exposed to strong light while shaded areas experience just a fraction of PPFD seen by the topside areas. Hence, a PAR meter could report 1,000 - but turn the probe upside down and you'll see what a shaded areas might experience. A third point - coloration, especially the non-fluorescent chromoproteins. The are often mauve, purple, blue, reddish. If mauve or purple, the preferentially reflect blue and red light - those wavelengths essential to photosynthesis. Obviously red and blue pigments selectively reflect light important to photosynthesis.
