Yooper (the op recipe) said she used a thinner mash to combat the ph so I was gonna use the same method.
Well, that all depends on the alkalinity (hardness) of the water being used how much your grist can help to counteract that.
Our general mash pH target is 5.2, as measured
at room temps. A deviation of 0.2 pH (or even 0.3?) up or down is acceptable, or sometimes preferred, depending on the beer being brewed.
Grists containing a higher percentage of dark roasted malts (which are more acidic) tend to drop mash pH, offsetting higher alkalinity in the brewing water. That's why most brewers with naturally high alkalinity (hard) water can brew dark beers more easily than light ones, without tinkering with water chemistry.*
Even when mashing grists containing a good percentage of dark malts, very hard water may still result in raising the
mash pH too much too. This can happen when used in full volume BIAB. Using only half or 2/3 of that hard water could work better. Or "dilute" your hard tap water with RO or distilled water.
When hard water is used in
sparging, it will always need to be acidified to keep the grist pH low enough (pH< 5.8) to prevents extracting (unwanted) tannins, silicates, and such.
* On the other side, those who brew dark beers with low alkalinity water, often have to
add carbonates/bicarbonates to prevent the mash pH from dropping
too low.