Lemon Haze Auto

I started this week my second hydroponic plant, a Lemon Haze Auto. I'm using a DWC system with 3L on beginning to start the roots without lost some much ferts. I had some problems on my first hydroponics with PH and temperature. The PH was rising up faster but I controlled that with help of one dude from here. But I still having problems with temperature because it's summer in Brazil and the water temperature is around 28º/29°c. I will try use a peltier system to get down the temperature. Well, the ppm is around 200 and the PH is 5.6.