Dude anything about 72 degrees and your going to have algae and possibly root rot. Ideally you want a constant 68. If your not using RO (reverse osmosis; read 4ppm instead of 150-300 of tap water) then you are even more at risk for algae. Bacteria sucks. Summer water can be the worst.

pH of 5.8 almost always. Make sure you test this often, especially if your water comes out high. pH down will only work for so long. Check your pH AFTER you put in your nutrients. Check it another 30 minutes afterwords to doublecheck. Do this until your confident in how much the pH changes in those 30 minutes (sometimes none, sometimes .3 points!).

hydro is not the best beginner growing project in my opinion. A lot more things can go wrong. PS. The clay balls are called Hydroton. They are made out of kilned clay, thats what the roots grow onto and around and what they hold onto. They are very good at displacing water.