Am horrible at suggesting placements for acros as most of mine always brown out for months in the beginning and then start to color up .
Its kind of complicated to suggest placement unless you can tell what PAR do you cover in the tank.
Echinatas will do fine in a little lower PAR of 200-250 (mine is currently browned out , not sure why .. may be because I keep moving it )and humilus will love lots and lots of flow .
Pikachu loves getting blasted with light . Mine is at the highest point with ORA Pearlberry and Oregon tort receiving around 600+ PAR from radium halides..
Paletta Pink Tip - well I scorched mine in too much light .. If you want green body, better to keep it lower .
Torts - If oregon, blast it with light but all very very slowly.
These are just my experience .. I have seen echinatas amazing blue in high PAR of 400-500 + .
Light is only 1 small part of the equation . I think , flow placement is as important if not more especially for acros like Humilus .
Also nutrients and alk - how high do you run your nutrients and Alk?
Regards,
Abhishek