Mash pH too low?

I've been experimenting with water adjustment, and for the last 3 brews have been getting pH of about 4.8, at mash temp. I'm brewing IPAs with SRM according to BTP of around 13, using 2-row, and various amounts of rye, MO, vienna, and Crysal 60.
Following are my water parameters:
Initial Adjusted
(Ca ppm) 3 190
(Mg ppm) 4 15
(Na ppm) 6 47
(Cl ppm) 0 109
(SO4 ppm) 7 135
(CaCO3 ppm) 221
RA 77
Cl/SO4 ratio 0.81

Does the low pH reading make sense? Is it okay or should I try to bring it up? If so, how - by adding chalk and/or baking soda to bring it up?

thanks

I'm a newb at this myself but from what I can see your water is good for that SRM without adjustment. It may depend on how you adjusted your water to get those final numbers. Did you add things like calcium carbonate/chalk or baking soda that raises RA? or did you add things like gypsum, calcium chloride, or epsom salts that lower it? If you only added things that lower your RA it may explain the low PH.

To answer your question though 4.8 PH should still work, but alpha amylase won't like it that much, beta amylase should be happy though. It may mean that your conversions take a little longer. Low PH my affect the mouthfeel in the finished product as well.

Adding things that raise your alkalinity like the chalk and baking soda you mentioned will help drive the PH up to the desired range.

According to my ph strips (who knows how accurate) my mashes never exceed 4.8, even with water additions, and my beers come out good, as a matter of fact very good.

I wonder about my pH at times. I've used the test kits from the store for pH and Alkalinity. I've used the ones from my pool. I've used test strips. They all say the say thing. My pH is right at 6 before mashing. While mashing right at 5.5.

The report from my water company says my pH on average is 9.75. I've tested in all seasons. So I wonder if the reading they take at the plant is bogus for our applications as it has to travel quite a way to get to me.

Just thinking out loud. Didn't mean to highjack.

Thanks for the feedback.

UP what you said about beta vs alpha makes sense. Palmer in How to Brew writes 'a beta-optimum wort is not a very fermentable wort'. I would infer that therefore a lower pH wort (more beta) would see lower attenuation and higher FG. I would have further thought that this would result in more mouthfeel, but perhaps mouthful is not a function of more remaining sugars - I really don't know.

I had been (prior to water adjustment) been getting >80% attenuation out of US05, but have recently been mashing hotter (shooting for 154) plus the water adjustments, so I will have to see what sort of attenuation I'm getting under these recent conditions.

To get to the water parameters I reported, I added the following:
Adjustments (grams) Mash / Boil Kettle:
CaCO3: 6 / 6
CaSO4: 4 / 4
CaCl2: 6 / 6
MgSO4: 3 / 3
NaHCO3: 4 / 4
NaCl: 0 / 0
so there is some competition between RA-increasing and RA-decreasing salts going on.

Regardless, my beer tastes pretty good in the meantime, so I'm happy.