hey balanca, check out my summer grow diary, basically ihad the same problem during my first grow. basically if the temperature outside the tent is above 25 degrees there is very little you can do actually. the most important thing is to keep the root zone cool. So more fans on the bottom of your tent. Personally i used a 1KW/H A/C system, but you can do very well with an "evaporative cooler" which is a much cheaper alternative at least you're using LEDs, i was using HID with a 1330m3/H . Even though you do use LEDs you still need a pretty big exhaust, and make sure your carbon filter is big enough to let the extrator pull enough air through. Hope this helps ! đ