Anything lower than 6500k is not suitable for marine.other than that,its really your preference.most people go for 10000k as its got a crisp white colour.any lower would be yellow and any higher would be bluish.
can you list down the number of equipment you are using that will increase the heat of the tank(e.g lights, pumps etc..) and how long does it takes for the chiller to cool your tank down to say..... 25c?
thanks!