Thank you, I have a hard time figuring it out, I either keep them too long at lower light or bring them up too soon sometimes.it really depends on the system - being that each reef is different we recommend starting acros on the bottom 1/3 of your aquarium and working them up the rockwork over the next few weeks. Also keep in mind each acro is different so some may be happy in that bottom 1/3 region while others may enjoy the tip top and so on