Well my friend. u have already answer your own Qns.
U already decide not have have a chiller for your zoa/tank.
well, i have try and bring down my 1ft tank to 27 with fan on cool day/night, 28-29 on normal day. Top up with 500ml or more daily.
Colour of zoa depent on lot of factor like light(increase heat to tank), NO3&PO4 in the water, Pest in the tank, Placement of coral.
Maybe you can try to find some zoa info under the soft coral topic. a lot of good advise from the zoa pro, or get help from the zoa doctor(some of us know who he is )