Am I Overfeeding?

[Letterhead954]

My latest batch of plants in veg have been growing very, very slowly. Recently I gave a couple of plants to another patient and he said that the leaves on my plants were much darker than on his, and his were growing normally. I put the worst plant in flower last night, and was amazed at how dark the leaves were compared to another plant that had been in there only two weeks. I have one plant in a bubble bucket that is growing like a weed, and it's leaves are noticeably lighter than the other plants in soil. There is no sign of nute lockout or burn, though for the first time in veg I noticed that some plants have developed 'the claw' on some of their leaves. While I follow the GH chart, could this be a sign of overfeeding? I always feed, water, feed, water, and am growing in Roots Original. Ph is between 6.0 and 6.3, though another grower suggested I up it to 6.5. I use tap water that I let set out for 24 hours before using. Temps were averaging in the mid-80's and are now in the mid to upper 70's. RH is typically 45-55%, though lower now that fall is here. Ventilation is good. I tested the ppm's a couple of times, and it was running around 1350, but my tap water run's at about 225 to start with.

Any help would be appreciated.