What soil are you using? Get yourself powdered dolomite lime, it buffers low ph. You can either mix some into the top of your soil or add it to fresh water (it won't dissolve) and water. If you gonna mix it with water i would suggest doing it 2 or 3 waterings. It won't affect your ph immediately but i would say over 2 to 3 weeks and it will keep your ph in check till harvest if done right. Plus dolomite lime also adds calc and mag.
It might show small effects now but if you don't act soon you will run into major nute lockouts.
Good luck