Coral Colours and Amino Acids

[Ron99]

Things in the 75 gallon are going so so right now. I am finding that the zoas are not doing well and slowly withering away. Also my SPS is not very colourful and browning out in some cases. I have an 8 bulb sunlight supply T5 fixture so I don't think light is an issue. Most of the bulbs are only a couple of months old. Parameters look to be in the normal range (i.e Ca, Mg, Alk all look okay, nitrates and phosphates unmeasurable etc.).

I did a bit of reading and am thinking maybe i don't have enough fish poop/amino acids in the water. Currently there are only 3 fish in the tank, a six line wrasse and a true perc/false perc pair. So maybe the bioload is to low for 75 gallons (plus 11 or so gallons in the sump) and I need to supplement the amino acid content somewhat? Any thoughts would be appreciated.