Thanks for the advice guys and girls, I'm abit low on cash, so I'll probably have to stick with the MHbulb for the meantime. Anyway, Here's the plants this morning. I fertilised the plant's again with Phosphrate fertiliser and the yellow leaves havn't gone. The new leaves are starting to get yellow tips, so I think the problems getting worse. It can't be light burn because the other plant is at exactly the same height, anyone got any idea's?

Anyway here are the pics, look out for the yellow tips on the brandnew leaves on one of the plants.