Using trichlor pucks is probably your culprit as they are extremely acidic and will drive your ph down. When your ph appeared to drop to 6.8 earlier, it might actually have been much lower than that as most test kits don't show anything lower than that reading. You don't mention what your cya reading is, but if you have been using trichlor it may be really high. If that is the case, a chlorine reading of 2 is pretty risky. At any rate, continue adding Borax. Wait 4 or 5 hours between doses to let it mix well, then retest and redose until you get your ph between 7.4-7.6. Also, test for your cya level and repost with that info. If you find that your cya is really high, you might want to consider using something else other than the pucks to chlorinate with as they will continue to add cya. Hope this helps.