Rio 1400+ Output

[davidncbrown]

Like the topic says, I have a Rio 1400+ I am going to use to replace my crummy powerhead for my chiller. It is listed 420GPH with a 6.5ft max head. The tubing for my chiller is 1/2" dia and the output of the Rio is 3/4". I was thinking about stepping down the output with a small section of 3/4" tubing and a 1/2 to 3/4" coupling. Would this significantly lower the flow rate of the pump? I currently use the stock nano cube pump for circulating water through my chiller and I have the chiller turning on every couple minutes because it cools the water off so fast that the entire tank doesn't have time to cool from the small amount of water that just got cooled off. I figure running a higher flow through the chiller might help this. I'm taking water out of the 2nd chamber and putting it back into the 3rd right by my NC's circulation pump. If anyone can tell me whether this is feasible or not I'd greatly appreciate it.