Adequate Power Supply for 300 Daisy-Chained LEDs
Afaik you are doing right.

300 leds / (150 leds / 5 m) = 10 m of LEDs. 10 m * 9 W/m = 90 W.
So 200 W is more than twice you need.

The reason you get color problems, is that the voltage reduces halfway so much, the LEDs do not have the entire 5 V but less.

By splitting the complete circuit in two, you reduce the voltage reduction, but probably not enough, you might to split it in four segments if possible.

By doing this, you have 4 segments of 50 W, but you also need  90 / 4 = 22.5 W per segment.

(probably there is a way to exactly calculate how many LEDs in one chain you can power with a certain PS but some more variables are needed, which I don't know).