LPS color fading

[John Zillmer]

I have experienced variable color fading in LPS in my display system. Euphyllia and Caulastrea hold their green color well, but a nearly solid green Trachyphyllia has become striated in color (green radiating stripes alternating with reddish-brown tissue), and a red Lobo and a red Symphyllia have both become dirtier in color over the course of about 6 months. FWIW, all the color-fading animals were taken in as rescues -- the Lobo had 50% recession in the store (I ended up fragging off one polyp which is healing ver nicely), the Symphillia had about 25% recession when I got it (which was improving until I tried GFO phosphate media -- increased the recession to about 50% and bleached a couple spots. Bleached spots have since reacquired normal color after discontinuing the GFO). The Trach had been burned on two sides, but has good enough expansion in my system that there is no further recession.

The tank is a 10 year old 55g lit by about 160w of boosted T-8, with 50% 10K, 25% actinic and 25% 6700K -- I run lower K temps for growth of softies, leathers and corallimorphs (which, BTW, have suberb color). Minimal skimming, no fuge. 10% w/c 2X/week. Nitrates 10ppm, pH 8.5, KH 8-10, SG 1.025. The LPS get fed a couple times a week with brine and mysis spiked with Kent Zoecon, and the tank gets a lot of food (for a couple Tubastrea colonies and a pair of Synchiropus).

Is the color fading due to the relative lack of actinic light, or to diet? I'm thinking I'll improve their diet first (since I really do like the lighting set up in all other regards) -- add some Cyclopeeze into the mix, and alternate with chooped krill. Any thoughts or suggestions?