6.2 is about what I run mine but technically I don't ph it but 1 or 2 times per grow, I get my water from the same source every time. It tends to be in the low 7 range, after adding my nutrients, I can pretty much count on it falling into an acceptable range... The soil I use is that nature's care organic... It's like a blend of soil and coco, and you can't really over water it... Well it has ph buffers in it also, or at least that's my guess, so I'm pretty sure it hits a multitude of different ph ranges.. Which in my opinion is better.