Maybe basic questions but..... Are you using RO, RO/DI, tap?.....do you know what the TDS of the water you are using is?.... Have you tested the water for phosphates? .... Nitrates?..... Any leathers in the tank..... And I know you said you've never seen your angel nipping, but that doesn't mean that it isn't happening
.... It seems that fish somehow know when you are watching and put their halos on
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260g mixed reef, 105g sump, water blaster 7000 return, Bubble King SM 300 skimmer, Aqua Controller Jr, 4 radions, 3 Tunze 6055s,1 tunze 6065, 2 Vortech MP40s, Vortech MP20, Tunze ATO, GHL SA2 doser, 2 TLF reactors (1 carbon, 1 rowa).
http://www.canreef.com/vbulletin/showthread.php?t=50034 . Tank Video here
http://www.vimeo.com/2304609 and here
http://www.vimeo.com/16591694