they turn purplish and can even border on being completely black.
The tale of 2 aclandiae
I have 2 of these one on the top shelf in high light and the 2nd on a lower shelf unit outdoors in the same rack but gets a little more cover from the surrounding plants.
The one on top that gets brighter lights new growth (1) came out almost black it was so purple. Its starting to turn back to green but its looking more like the remnants of a bruise with it being almost yellow.
The 2nd one got lower light and stayed pretty much green and shot out 4 new growths all looking normal green. Ill get pics of this and show you what I mean. I might seem haphazard in my approach to some but I can still tally results
So my feel on this is too much purpling, the plant spends a lot of energy producing this for protection. It doesnt hurt them but re allocates the plants energy output to purpling the leaves.
While the other one grown under slightly lower light has put out more growths bec it didnt have to protect its leaves and spent its energy making more plant.
There is a fine line between too much and not enough and that line is Just Right
I really cant say about whats happening under your lights but I myself in 3 years have never bloomed one under lights in any condition purple or not. Always been outdoors with these.
but good luck they are nice flowers and worth waiting for