Rainbow Acro, Should I be Concerned?

[Sig32]

I would like some thoughts and opinions on what I have going on here, please. Below are my measured tank parameters (Red Sea Pro & Hanna kits). This is my first adventure into SPS so I really don't know what if anything is wrong with the coral.

65 Gallon mixed reef
Phosphate: 0 (I know I have some because of some algae on the sand)
Nitrate: 0
Alkalinity: 9.6
Calcium: 450
Magnesium: 1460
pH: 8

These have been consistent measurements since the tank cycled earlier this year. I put this rainbow frag in my tank three weeks ago and it was brown (it was recovering from a power outage). From the beginning, it has had the polyps extended and has shown no signs of stress. About a ten days ago I started noticing the coral began to lighten up (expected would happen) and then I started to notice one area on the main trunk where it branches was much lighter than any other part (see photos below).

Is this normal or is something wrong? Its encrusting on to the rock faster than any of my other corals and the polyps are still extended throughout the rest of the coral. In the light colored area, the polyps seem retracted though. Should I be concerned?

 

[murphreef]

I would work on lowering your Alk to mid 8's

Also what lighting are you running? I find led's and high alk can really lighten up a coral

 

[macdaddynick1]

Acros, as well as any other coral need po4 and no3. Some tanks run 0 no3 and po4 because the turnover of those are high in the tank. Meaning even if someone with a very mature tank feeds a lot, the bacteria and corals consume those fast enough to keep them low. In the less mature tanks if your parameters are at 0 it's usually because you barely feed the tank and it could starve the corals. That being said if you feed way too much your no3 and po4 will skyrocket . So I would suggest feeding the tank just a bit more. Also, acroporas are known to be quick to brown and hard to color back up. Especially if this coral is Vivid's rainbow delight, that acro is notorious for browning out or losing color.


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[Sig32]

Totally forgot to add that, sorry. I am running LEDs and have them ramp up to a max of 30% blues and 15% whites for 4 hours in the day and then down to off in the evening. They sit in the hood so they're only 6" off of the water. I don't have a par meter so I am not sure if I need more or less light. My other corals seem to be fine in the sense that they're open and not closed. Based on that I assume I'm in the ball park with intensity, but I perhaps not at optimum levels.

 

[murphreef]

I have to agree with Nick

Your tank looks young and looks sterile. How old is your set up?

Sometimes takes over 6months for a tank to mature enough to keep sps super happy

 

[jda]

You have N and P... don't worry about that. Nobody has zero unless you are doing vodka or vinegar in a really aggressive way.

That is not very long of a light cycle. The coral are going to need 8 hours of solid light.

Is that lighter spot with the color happen to be a place where the acro is shadowed by the branches above?

All acropora are hard in young tanks. I would not chase this too much - this might not be you and just a product of a young tank. When the coralline start to grow like crazy, then acros are usually a lot easier.

 

[Sig32]

Thanks for the replies. The tank is very young still, ~4.5 months. I'll definitely increase feeds to help them out. As for the white area, is it ok or bad news? What do you think it is?

 

[Sig32]

jda, the lighter spot is at the base of the branch, but I don't think the branch's angle is low enough to block the light. As for my lights should I increase the total hours of maximum intensity or slowly increase the maximum intensity to greater than it is now but keep the current duration?

I assume that since it's encrusting it's at least doing well, correct? Also, I am finally seeing spots of coralline on my rocks, but not growing like crazy yet.