how to bring water temps down in aero cloning

[trichnut]

iv got the aeroponic power cloner and my water temps have been quite steady at 81 deg. im thinking of cycling the pump to go on and off but im not sure what the time frames should be. was thinking 5 min off and 10 min on. id really like to see my temps down in the low 70s. any one else doing somthing like this?

 

[The Hemp Goddess]

I have a cycle timer--1 minute on and 4 minutes off. Water temps are never an issue.