That looks great and you are only shading some sand that way. Nice placement.Is that an efflo? I love large colonies.
You called it. It measured 8 x 9 "
It is directly in the path of one of the MP60's. There is also a reef wave on the top of back the glass that is angled down. So much more direct flow that I expect will reduce the detritus settling.
I have a piece of PVC supporting it. Before attaching to the rock I like to prime the rock by scaping any corralline away and exposing raw rock to interdigitate with the glue. I find a ringed curette and rongeur the best instruments to do this. A bone cutter can work as well.
Once the rock is exposed I used a generous amount of coral glue to attach to the rock. I then add putty to provide futher molding and support.
Not sure if there are other tricks that might be helpful. I'm planning on giving things 24 hours to cure and remove the pvc support.
I left about 5" from the front glass. Maybe a little closer than ideal. I'll likely shift around some LPS still and bump up the flow a little as well.
That was a pic of tricolor valida. It is funny, I have other chunks of it that grow more vertical than that one chose to, but with enough light they start spreading out.