My troubles seem to have resolved since I switched salt mixes. I now use reef crystals which has a vey high alk (previously used tropic marin and red sea which have very low alk levels). When I do water changes the corals respond very positively - increased polyp ext, better feeding response at night, full tissue expansion, etc...
The high alk of reef crystals has slowly brought my alk from 6.5 to currently around 8 and everything seems to be loving it. My ca reactor is running at nothing more than a maintenance rate to keep my alk from decreasing at all. The corals have shown new growth that I haven't seen in almost a year. Corraline algea is finally starting to grow. Everything seems much happier in many ways.
If I try increasing the ca reactor effluent or increase ca/alk dosing in any way the corals still get very irritated, but as long as I only use the supplementation as a maintenance dose then everything is happy. Since everything is happy right now I'm not about to screw with a good thing by experimenting any further. I'm content leaving it as a mystery and will chalk it up as yet another complex issue that I was able to eventually overcome.
Then there is that continual question in the back of my mind...... What if I tried changing things a bit to get even better growth rates. Something like using kalk as a supplement instead of the ca reactor because it has such a higher pH. That might increase growth rates further.....

I'm going to ponder that thought for a few weeks. I can't ever stop monkeying around with some aspect of the tanks chemistry. LOL!!
Jeremy