how much of a water change are you doing? alk seems fine and i wouldnt think a lack of dosing calc would bleach it out... especially if jack has the same issue.
honestly... Ive heard a couple things about Validas.
1st) they like a ton of flow... back and forth, up and down, but all DIRECT. less flow ive seen they just brown/fade/bleach out
2nd) they like it high up near the light but only if it gets alot of flow... without flow the coral needs a lower placement with direct light
3rd) they like water a little dirtier. heres some others about it... but I have a piece and its a small frag, but i dont run a skimmer currently... my xenia and Valida love the water conditions... but people who run powerful skimmers, clear tanks and dont feed the coral have had bleaching/fading color problems as well as growth issues.
http://www.reefcentral.com/forums/showthread.php?p=19387287
Im not saying to stop the skimmer, by any means, but maybe feeding the tank slightly if you dont, or giving it more direct flow will help.