6.2 is within your limits.......you mentioned you are using bottled water? It may be a touch low but your plants look like they definitely have issues.

If you are not using tap water, perhaps you should try it. Check the ph and when you water try to keep ph up a bit (about 6.7) to compensate for the low runoff. I know Stinky doesn't like using bottled water but I can't quite remember why......lots of salt in bottled water or missing certain micro nutes or maybe both.

Another thought is to completely transplant them all into a good quality soil like Fox Farms or something. New good quality soil and a transplant can fix a lot of issues!