Corals turning brown

[Zer0.]

I have a 180 gallon tank been up for about 5 months. Have an RBTA, a few fish and an assortment of LPS and softies.

Ive noticed my green duncan and my green purple tip frog spawn have turned a bit brown. I also have some eagle eye zoas whos skirts have faded from green to a pale yellowish green, although my darker green orange and brown zoas are looking good and have multiplied.

Tank params are;
1.025-1.026 SG.
77 F.
alk. 8.9 dKH
calc. 460 ppm (have been waiting for this to lower, salt mix mixes high calc.)
mag. 1340 ppm
po4 .02 ppm
no3 12-16 ppm ( hard to read my red sea pro kit, color always looks more light purple than light pink)

Running 3 modular 165 watt full spectrum LEDs over it @ 10% whites and 55% color (blue and a couple red and green), running 10 hours a day (was running 12 hours a day until a week ago and decided this might be too long) The corals had turned more brown before this btw.

Thanks for any input I'm not sure

I'm thinking the brown coloration is from the no3 or the lights are not intense enough. I have struggled with knowing how to set these lights.

Thanks for the longish read any advice. This is my first salt water tank and I really appreciate everyone's help.

 

[whosurcaddie]

The nitrate is fine your not in the danger zone there. Can you post a picture of the lights I'm not sure what you mean by modular.

 

[whosurcaddie]

Just to add the zooxanthellae in a corals tissue is usually a golden or brown color when a coral turns brown its overpopulating its cells with zooxanthellae to compensate for not having enough light. So lighting may be an issue here.

One more question do you have any algae in your tank that could be keeping your phosphate reading low?

 

[Zer0.]

The nitrate is fine your not in the danger zone there. Can you post a picture of the lights I'm not sure what you mean by modular.

They are the aquamana lights I believe you have or at least had.

Only have them mounted 7 inches up off the tank, kinda close.

 

[whosurcaddie]

Oh yeah I remember that. My coloration is doing fine I've been quite pleased with them. I have them sitting about the same distance as you also. One thing I have done though is increase the white to 20% and color spectrum to 70%.

 

[Zer0.]

One more question do you have any algae in your tank that could be keeping your phosphate reading low?

Just a tiny bit on the back wall little bit on a rock or two, really nit much.not running any po4 elimenation either tho. Checked po4 with red sea pro and a hanna.

 

[Zer0.]

Cool. I'm thinking the lighting might be a bit too low then. I take it I should raise them slowly. Would that be like a 2-3 % increase a week? Also how long do you run them if you don't mind?

 

[whosurcaddie]

I think its the light then. Try upping the intensity, a small change can reduce the number of zooxanthellae present in a corals tissue. It will take some time though. I know it sucks nobody wants brown corals but it doesn't mean they are unhealthy. Increase 20%white 70% full spectrum and give it a couple weeks.

I know firsthand these lights are more than capable. I bought a 10$ frag of brownish green zoas they were under Maxspect Razors at the reef shop and now after a month under my lights they have changed from a dull brownish green to bright green skirts and bright orange centers.

How deep is this tank?

 

[whosurcaddie]

The 3x3watt blues come on at 11am and the full spectrum comes on at noon then full spectrum off at 8pm and the 3x3 blues off at 9pm

 

[whosurcaddie]

Cool. I'm thinking the lighting might be a bit too low then. I take it I should raise them slowly. Would that be like a 2-3 % increase a week? Also how long do you run them if you don't mind?

No go ahead and make the full change you are only upping 10% and 15% that's not enough change to bleach corals.

 

[Zer0.]

I've never see bleaching, but I've seen my RBTA spit up some zoo after raising lights up a bit before. Really don't wanna get it relocating. It's stuck so far to where I first put it.

 

[Zer0.]

Will corals just be a bit ****ed off for a few days?

 

[whosurcaddie]

Will corals just be a bit ****ed off for a few days?

They will be fine. You only normally see a change like that when you go say from t5's to led's.

 

[Zer0.]

Caddie this is probably more visual preference than matters to the coral but do you leave your 3 x3 moonlight blues on for the full spectrum period?

Thanks a lot for a all the help. I like these lights a lot they are a great deal for the price, just sucks there is no docentation such as par value etc.

 

[whosurcaddie]

Yeah I got to find a place that rents out par meters so I can get the full picture of whats going on. Yes They are the first lights to come on and they stay on all the way through the full spectrum.