Jan's right: if your FC is high, it give false HIGH pH readings, not false lows.

You can add a couple of drops of chlorine neutralized to the sample before you test it, or use the Taylor 0014 pH test, rather than the 0004, because it has neutralizer.

If your pH is UP to 6.8, you need to raise your pH asap. Try using Borax instead of Washing Soda (Sodium Carbonate). I'd add a box, SLOWLY, into the skimmer. Wait an hour and check pH. iF it's not over 7.0, add another box and repeat.

Good luck!