Keep water under 68 f. I keep mine between 63 and 68 during the first couple of weeks.. then I go as low as 58 to 65..as the grow progresses.
See that pic I attached to the original thread? That is a 5 gallon bucket inside of a 10 or 12 gallon blue tote. I fill the blue tote halfway with reg. water. Then I use ice bottles to help regulate the water temps.