StealthHawk - I would say 65 - 70 for water temperature would be better. I believe 68 degree fahrenheit water holds a large % of dissolved oxygen. As the temperature of the water rises, it is unable to dissolve as much oxygen gas - so your plants will have less breathing air available! Higher temperatures with less dissolved oxygen is also a better environment for bacteria! Try to keep your temps down and happy growing!
edit: I agree with AFKA on allowing the PH to drift a bit. However I have never adjusted down to 5.2 The lowest I have gone is 5.5, and allowed it to raise to 6.4 In my experience with my DWC I have found my strain of plants likes to drift from 5.8 to 6.3, at 68 - 70 degree water temps.
I have forgotten how to find all the charts on rollitup :S my bad.. this is the only one I could find. But you'll see that you'll be alright in a range. Don't continuously add PH up or down to hit one specific number. If your PH is between 5.5 and 6.0 in my opinion, you will be fine! https://www.rollitup.org/general-marijuana-growing/287232-ph-chart.html