first think...
how manage the water...
Thru test kit, make sure u got a very good salt wiv all the nutrients
Check PH, KH, NO2
Good filtration system - sumptank, canister or hang on filter replace the carbon filter wiv bio rings.

second....
the best ligthing...
for 3 1/2 fit tank...
For coral normally is metal hydrite but it will warm up the water, then T5

third....
why the life coral die...
Because no chiller, normally cost additional RM 900 - RM 1,200 with 6 mths or without warranty.

Well the cost to maintain a coral tank will be higher due to the fact of higher electricity consumption.