Thank you for the natural light photo, thats a good first step. For us to fully understand your issues though we would also need you to fill out the 'patient form' in the main infirmary page.
Although pH could be a factor, this looks more like just plain hot nutes. Burned tips alone are not a bad thing, but if you see it get worse and progress than the nutes you are feeding are strong or the soil you are in is too hot.
To clarify,
burned tips show that you found the plants limit for nutes.
if the leaves start to crisp up farther than reduce your nutes or feed plain water once.