pH through out the process

Just want to ensure I have all the right targets for pH , assuming a lager beer.

When I mash I want 5.3 pH + or -.
Once I finish sparging and before I pitch my yeast I want 5.3 as well + or -, Correct or am i off the mark? Never measured this but if I add water will my pH not change drastically?

I have also “topped up” my wort with RO water before I pitched the yeast, is this bad and will it cause pH issues? I heard a lot of brewers do this.

I don’t have a very good pH meter but have ordered one for my next batch and want to get everything right for pH.

Thanks for your help!

Yes, that mash pH is appropriate when measured at room temperature. I’d suggest that the pH range could extend to 5.5 with little effect.

Topping off with RO or distilled water is unlikely to significantly affect the subsequent wort pH due to its low alkalinity.

Don’t fret too much over pH. This should be one of the last thing a brewer worries about. As long as you understand your water and have a rough understanding of its hardness and alkalinity, you can get get an idea of the types of beer that your water is suited for.