IMO get the digital ph pen and stay away from the cheap probes. Just out of curiousity, How do you water? Tap or distilled? My tap water runs about 8.3 most of the time so a good pen really helped me out (milwaukee 600 on ebay for 20 bucks). If you are using distilled you should add a little calmag from what ive read. I never used distilled so im just telling you what ive read and not from experience. I think those babies are gonna perk up after you get the ph and the heat problem solved. What kind of soil are you using?