Alkalinity at 11 is too high. It could be ok but it could also cause a lot of RTN and STN if your level of nutriment is low and juging from your test, you have low nutriment.
You should keep your alkalinity at 8 or around 8, not more than this when you have no amount of nitrates and phosphates detectible.
I think this is your problem and why your SPS bleached, alkalinity shock with low nutriment system.
I could be wrong, but this is my guess, also your calcium is far from being spot on, and this also could be a problem, as well as the low mag.
I would try to keep the alkalinity lower though.
You should rise your magnesium before attempting to rise your calcium because no matter what amount of calcium you put in there, it won't rise if your magnesium is that low. First raise your magnesium to 1300 or a bit more, then rise your calcium to 420, then try to lower the alkalinity to 8 and you should be able to keep SPS no problem.
Quote:
Originally Posted by nanomano
well I dont know about the params in the other tank, it was from RC in edmonton, so I'd assume the params were good, but I couldnt be precise on the numbers 
but mine are
ph 8.2
CA (low) 320-340
Alk 11
nitrates and nitrites 0
ammonia is 0
phosphates 0
dont know about my magnesium, but I know it has been lower around 1095 in the past.
Salinity is 1.025-1.026
edit, guess they arent "spot on" since my CA is a bit low, and mag is most likely low as well, it usually has been. I have some Reef advantage Calcium(Seachem) that buffers ph and Mag, and Strontium |