Do you have PE at night?
I am am suspect to think high light is a potential, as well as too much flow. Afterall, if specie like milli and prostrata seem to have more PE with more flow, there should be specie that it inhibits.
See surface area in this article, it sparked my curosity. (By now you can probably tell what I was reading and where tonight)
http://www.advancedaquarist.com/2006/6/aafeature2/view
This a begs the questions: Is PE a good thing, is it a bad thing?
Though aetheticaly pleasing, in which I try to obtain as well, to understand how to achieve it we need first to understand WHY it is happening, which seems less apt to hair pulling than spending time chasing a really cool fish to take out that adds more to the tank anyway. Right?
There are some who believe the bubble tips of a BTA are signs of stress, which explains why they disappear over time in captivity. As well, the over inflation of an anenome could be a sign of malnutrition as it is attempting to increase its surface area for light collection. These also historically have been coveted signs of "good health" that we could be incorrect on.
Some of my PE is great, other completly suck, and I think falling out of the corralite PE is harder to achieve on all your piecies during daylight hours that it is to have great coloration, which we know is hard to achieve sometimes as is.
If you like your fish, don't get rid of it......I don't think I would give up my Potters Angel for anymore PE. Just comming to terms with it I suppose, and letting you know that your not alone in these SPS struggles.