I'm still confused........exactly how are you checking your pH? Specifically what kind of pH meter are you using? Is it for testing water or soil?
If you are using one of those 2 prong testers you stick in the soil (who is HF?), throw it away--they do not work at all and are therefore worse than useless. What kind of pH up did you use? I cannot imagine going from 3 to 6.8 with 1 dose of pH up.
I also just looked up the Fafard's organic soil. It appears to me that the soil is prenuted as it says it comes with organic fertilizers in it. This could be causing problems. The soil is supposed to be between 5.5 and 6.5 after wetting. I would be quite surprised if it really was 3--I suspect your pH meter, however new plants do not like prenuted soil.