Adjusting pH in Your Mash when Homebrewing 

I usually add a bit of phosphoric acid to my sparge water as an extra step, but I do this more for the flavor profile than for the possibility of extracting tannins, as I usually batch-sparge (so the gravity of the final sparge is basically a constant). I really like the crisp mouthfeel that the added phosphoric gives my beers, and I understand that this is also better for both hop isomerization in the boil and overall shelf stability. General guidelines are to acidify brewing water to around 5.5 pH and, if fly sparging, always stop before you hit 1.010 gravity to avoid extracting astringent tannins. YMMV, but most people (I understand) don't usually have a problem with overly tannic homebrew anyhow, so this is largely a non-existent problem. *RDWHAHB.*

Say after 10 minutes into the mash you take a reading then add some acid, how long will it take to distribute through the mash so you can then take another reading?

I think the point you are perhaps missing here is that the mash pH has to be correct for the mash, so by the time you take your 15 minute sample and cool it to room temperature where it needs to be even if you have a ATC meter, it is already too late to adjust as the mash is for the most part complete.

well how do you get a higher ph if wine is too acidic i cant find no info on that

I need to start tracking my PH.

Have you ever used Five Star 5.2 ph adjuster?