ph problem

please let me know how to fix my ph level. two out of my three plants have developed yellow and brown small round spots on the fan leaves and the ph reading on them is crashing to the bottom of the meter. they are acidic somehow. my question is how can i raise the ph to nuetral. is there another way besides lime. there are only two weeks left in flowering. just fan leaves up to top have it.

Buy some ph up and ph down. Does not cost too much and is much easier than home remedys.