Anybody have advice for slowing dying off SPS (especially Acropora)? Over the last few months, numerous species of SPS that were thriving and growing/spreading quite nicely for a long time began to slowly all die back :-( The fish and other coral species, anemones, etc. are all thriving still. I dose with 2-part and use Reef Crystals for water exchanges. I have ROX/GFO in a reactor but admittedly, I go wayyy too long in between media changes. Interestingly, I had issues with cyanobacteria for quite a while and without any intervention, it starting to slowly die back during the same timeframe that my SPS also started to die off.
Here are my parameters:
Temp: 79-80 F
pH: ranges between 8.2ish-8.4ish in 24-hr period
SG: 1.024-1.025 (salin 32.5 ppt)
calcium: 410-430 ppm during die off (now up to 460 because all the clam and SPS losses; I cut back on my calcium dosing in response to this)
alkalinity: 9-9.5 dKH during die off (now up to 10.5 because all the clam and SPS losses; I cut back on my alk dosing in response to this)
phophorus/phosphate: 0.066/0.20 ppm
nitrates: 0
Seems like my phosphate is way higher than the recommended goal (I use an automatic feeder for my anthias, etc. during the day while I'm at work and may be the main culprit for this; I feed frozen at night). But the strange thing, knock on wood, is that I have zero algae issues! The more I've read about phosphates, it seems like them getting high is not ideal and causes algal blooms, etc., but it seems like maybe the jury is out as to whether it truly kills coral/growth (? inhibits coral skeleton growth?). Is this true or is this maybe what's killing my SPS? I was gonna go change out my ROX/GFO now and cut back on the automatic feeder use. It's so sad to watch all the hard work and money and hardscaping with the SPS frags that had grown beautifully all die off! Thanks in advance and I welcome any thoughts/advice!