Why do my LPS hate me?

[BlueWorldJeff]

I'm having some issues with my LPS corals as well as chalices and monti digitata.

First off, my parameters:
Alk 7
CA 450
Mg 1290
PO4 0
NO3 2-5

I use three (3) Rapid LED onyx LED dimmable fixtures. The blues ramp up to 100% and down in 12 hours, same with the mixed channel. Whites ramp up to 50% and down in 12 hours.

I have had GFO online but just today turned it off. Not sure if ULNS is good for what I am trying to accomplish.

Issues:
Favia - tissue receding from base, lower 3rd of tank
Maze Brain - tissue recession from base and burnt end, middle of tank
Hollywood Stunner Chalice - burnt on top, middle of tank
Montipora Digitata - growing very skinny with no polyp extension (Purple and Orange), top 3rd of tank
Torch Coral - low polyp extension, lower 3rd of tank

I have other corals that are doing very well:
Green Monti Cap - great color and white rim
Pink Prostrata - Growing well, but no polyp extension
Porites - growing, encrusting, good color
Hammer Coral - good polyp extension
Acans - doing well, maybe some BTN

I'm not sure if I should bring my Alk up to 8 and try to get some PO4 and No3 as long as its under .10 and 10 respectively. Seems like with low nutrients and low(er) alk, the lights burn more. I'd like my digitata to grow like fingers, but its growing like a tree.

 

[karimwassef]

Brain and Favia need low light. Move down of use different lensing.
Chalice and digitata and very hardy, but thrive at higher Alp,. Raise Alk to 8.5+, Ca 450+, Mg 1400+
Digitata growing like a tree usually needs very high flow so it's building a solid base. Shaded lighting creates few preferential locations - could also drive a tree vs. branches.
Torch - check flow, they don't do well with high flow.

Could also be a pest.

just my 0.02

 

[BlueWorldJeff]

Brain and Favia need low light. Move down of use different lensing.
Chalice and digitata and very hardy, but thrive at higher Alp,. Raise Alk to 8.5+, Ca 450+, Mg 1400+
Digitata growing like a tree usually needs very high flow so it's building a solid base. Shaded lighting creates few preferential locations - could also drive a tree vs. branches.
Torch - check flow, they don't do well with high flow.

Could also be a pest.

just my 0.02

Thanks for the info.

I have my favia as low as it can go in the tank, without being on the sand.

The maze brain and chalice are at the same level in the middle of the tank, about half way up. The LED in the middle of the tank is 100 degree optics where the end LEDs are 60 degree, so its less intensity, but those are the two that are burning.

The digitata gets good flow. Probably the most direct from a powerhead than any coral.

The torch is looking better, i moved it to the side of the tank and its slowly getting more PE.

I'm hoping turning GFO off will help in some way, either by allowing some nutrients or just not stripping the water of whatever.

I've read that alk at 7 is good for carbon dosing, but to stay around 8 or more for normal operation. Is there any correlation between nutrient levels and alk levels as far as tissue necrosis or burning

The BTN and burning are my major concerns