Hello Bigdaddy216,
First I would like to mention I have been extremely busy today, but I promise I will send you both those articles as soon As I can catch a breath. I wouldn't have even chimed in today except that I thought it was important to tell you a couple things. First, As I mentioned earlier in this thread there is no need to spend money on a electronic pH pen. If you have money burning a hole in your pocket, that's fine get one. I don't care if it's a cheep one, or the best on the market, they all have the same type of problems. The only reliable method to test pH is with pH drops. However the pH drops your using are the wrong type. They are not capable of the right pH range. The lowest it goes is 6.0, and You need a pH range between 4 and 8. Six point zero is perfect for most plants, but the pH can be 4.0 (not good for any plants) and those test drops wont be able to tell you because it cant go that low. This is what I always use, and is all you need (
pH Test Kit). You can get it at any hydroponics shop for under $10, and doesn't need to be calibrated, need to be adjusted for water temp, will never give you false readings, and last you a year or more even with regular use.
By the way pH for cucumbers is around 5.8 and 6.0. So 6.0 is perfect for them, but it may have been much lower and you would never know it using those drops. 6.5 to 7 is actually to high for cucumbers. Yes Like I mentioned your water temp is just fine between 65 and 70F. Optimum water temp is between 68 and 72, but a few degrees either way is no problem. However once it gets up much past 80 you'll begin to have problems. Some plants tolerate heat stress better than others, so with cool weather plants like lettuce you should try to not let it get higher than 75 or so.