Yellow spots and curled leaves PH problem....

Ive slowly been getting these yellow spots and my leaves have been curling. This problem has just started to happen. Ive been told that it chould have something to do with the ph level but i have been keeping it at a 6.0 the whole time. I also have been using a lil bit of superthrive here and there to see if it had any affect of the plant being this is my first one and im trial n erroring it....if need i can get pictures. And if it is the ph should i rise it or lower. All info is appricated.

If that is all you are feeding them, I would say they need some more nutes. How big is it? A pic would help too.