coral and light/flow level

[Reef Tank 2.0]

when you are buying/placing coral, do you place them based off the par readings, or do you place them based off of low, medium, or high light?

There has got to be an easier way of finding a coral a home, rather than constantly moving it around the tank hoping it likes it.  Maybe that's the fun of having coral.  But from what I can tell, you want to place it, and leave it alone.  I constantly fight with trying to find the right flow/light for each piece of coral.

I have (3) hydra 26 HD's on my 130 gallon. and I have (5) 1500 hydor koralia power heads. My lights are run at roughly 50-60% capacity.  No where near maxed out.  I have lost corals due to bleaching.  Don;t quite understand that one.  When I was looking in to lights, I was told, for the size tank I have, I should use the Hydra 52's in order to grow all types of coral.  I refused to get that large, and I stuck with the 26's. With my 26's not running nearly at full capacity, I could only imagine what the 52's would do.  Those lights would have to be completely off to avoid bleaching. the dimensions of my tank point towards 52's, but all of my coral disagree.  my tank dims are 6ft long, 18" deep, and 24" high (130g)

Maybe there are other things that cause corals to bleach, if so, please share.

Would low/high alk cause corals to bleach?  For the longest time, my cal has been at 400-420, mag has been around 1300+, and my alk was at 8.3.  As of late, the Alk has dropped to 7.7.  But that alk change happened way after losing the corals to bleaching.  I will begin dosing after my treatment of bryopsis is over (roughly a week). 

Maybe dosing is all I need, but as of right now, I have a lot of my corals under a rock in order for it to be happy.  My light levels are low, as I've stated, I find it hard to believe that every coral needs to be under a rock or practically in the sand in order for it to grow

[lazylivin]

Moving a coral from one tank to another can be stressful. If you can match the light the seller has it under it can increase percentage of success and reduce the move and wait game. With this caveat. Most Retailers are buying coral from a wholesaler. These corals are fresh from the ocean to the Retailers tank. Matching the retailers light intensity could steer you in the wrong direction. If you buy coral from a hobbyist that has grown that coral in captivity knowing the PAR they had it under can be a great benefit. High, Medium, Low is different from tank to tank and perception of the seller of what those values should be. It does give something to go on but Low light for me maybe High light for someone else or vice versa. Type of light (MH/T5/LED) also effects the coral as well as intensity. Buying propagated name coral you get the added benefit of Google search. Commonly you can find forum threads where folks document their success of that specific coral with pictures of their tank, details about lighting and placement. If you don't have a named coral learning the species type and researching that can help find a suitable starting point in your tank. Also to add, there is a significant connection to lighting intensity and tank nutrients. Probably the single most impactful thing to coral color, polyp extension and health. This connection is why their are different results from one tank to another and why some folks can barely turn light up and get bleaching where others can blast their corals and be just fine.

Below is some info I recorded in Dec 2014 to give example what you may find online with some Google searching.

PAR Readings Nov 2014 - 2x 400w 20k Metal Halide + 120w LED in center. Some corals are large which is why the PAR fluctuates so much from one end of the coral to the other. Low being the lowest recorded PAR hitting any of the coral branches and High is the highest recorded PAR on any of the branches. Sweet Spot is where I think the coral would do best. In many cases it is a guess based on the PAR the coral is in and the colors it is exhibiting or from lighting experiments with the coral in the frag tank.

AVG Parameters
Alk 9.5 | CA 420 | Mag 1300 | P04 .04 | Potassium 400 | Iodine .06 | Nitrate Less than 1 (Goal is 3-5)