I have another question for you guys. I need to add a chiller to my system because my temperture is swinging from 74 at night to over 80 with the lights on. I understand how a chiller works but was wondering if they have a built in powerhead or do you have to add that also? Also wondering if they heat the water when the temp drops below the setting? Also where does the water need to be pulled from and discharged back to? I was looking at a Arctica Titanium Chiller 1/10 hp. If there is a better unit please let me know. Thanks for everybodys help !!