Dark spots on most leaves, need opinions.

Hello. I'm 6 1/2 weeks into flowering with this indoor hydroponic plant and iv been having dark spots on a lot of my leaves but not all. Couldn't find anything on it so far so thought id ask. Heres a pic to show you. Thanks!

No one knows?

Either the pH is off or they just need food.

iv been feeding them once a week and keeping the pH around 6.0, should i change anything?