If your FC is only 6.4ppm, then your pH reading would be accurate. With a Taylor K2006 kit, pH tests are accurate with FC readings up to 15. But, if you have higher chlorine levels than that, you would need to dilute the sample (to lower the chlorine level) before testing pH. The amount of dilution depends on how high your chlorine is --- you need to get it lower than 15. You dilute with distilled water and then test pH as normal. The reading you get when testing your diluted sample would be your pH level.

Be diligent about keeping your chlorine readings in the proper range per the Best Guess Chlorine Chart (in either PoolDoc's or my signature box) and you should not have any algae problems.

Hope this helps.