thanks dude, what's your cf reading?

I've got them at 8 but dont know whether to push them up, some of the tips are a little yellow but most of them are a great green plush color. I think maybe I fert'd too early but they catching upto needing it now.
KHAN Reviewed by KHAN on . yellow tinting on leaves? Since I've put the NFT system on the plants have shown some good growth, I'm slightly worried that the leaves seem to be developing a yellowish tint, at the tips and edges. I've heard this could be a few different things, I dont think it's overwatering (since its in the nft system i hope not) Each of my tanks are 9 gallons, I have a CF reading of 6, a ph of 5.5 and have placed a little oxygen in the tank a few days ago. Here are some updated pics, any advice will be gratefully received ;) Rating: 5