Dying Torch and Unhappy Scoly

[joro]

I'm thinking you may need to feed more. A little nitrate is good for LPS. And if you have algae or other corals consuming it they're literally starving to death.

It explains the health of the other corals and the likely demise of these.

Sorry, I misstated the above. Nitrites are 0, Nitrates are around 5ppm. Do you still think I'm underfeeding?

 

[Elementalj]

Sorry, I misstated the above. Nitrites are 0, Nitrates are around 5ppm. Do you still think I'm underfeeding?

Well, we've exhausted just about every thing that could be a possible contributor. The only thing that may remain is lighting, irritation by a foreign body, or flow. Have you removed the corals and inspected them under good light? I'd also dip while I had them out of the tank.

The only other parameter that ticked my senses was the alkalinity being below the normal threshold. Since you state the other corals are fine I've been looking for observable approaches to the issue.

There is no evidence of brown slime bacteria? There are no visible irritants or parasites on the corals? Is the alkalinity normally this low? Have you had a heater or temperature control issue? Are things like salinity and temperature stable?