Never used the Kent's but I would first check the nutrients being introduced. I.E. how much and of what are you feeding? Most likely its too much food causing a buildup of phosphates and nitrates which the algae then consumes to grow. I would reduce feeding, possibly cut back photoperiod, add some phosphate/nitrate control (reactor with media), and make sure you have enough of a clean up crew. Will take some time but you will get the upper hand. Also PWC
regularly are your friend. Good luck.