"When i connect 5 together to make white (1*330 ohm resistor per red diode), they work fine. but when I connect a lot more, they turn red."
Suggests to me that your voltage is dropping too low for Green & Blue to turn on.
Usually that is a result of not enough current available.
How does the Arduino fit in? Will it be controlling transistors or drivers such ULN2803, or shift registers with high current capability such as TPIC6B585, to select the groups of LEDs to be turned on?