mash pH much lower than expected

[showcow]

Hi guys. I've been using 5.2 in all of my beers with great results for about 2 years, but I really want to get into adjusting my water by myself. That said, i'm having strange results.

Using Palmer's chart in the back of how to brew, my estimate is a pH of 5.75 at room temp (5.45 at mash temps). I just did an experiment that confirms my previos brew sessions without using 5.2. I crushed .5# of 2-row and added .75qt of water for a normal ratio of 1.5 qts per pound. I poured over water that was 165*F and got a tiny mash temp of 154. i waited 5 minutes and the temp was 140, so i put the pot on the burner and brought it back up to 154. anyway.

The pH read 5.0 according to my pH strips.

Now, i know it's hard to tell the color on those damn things, but there's no way i'm 4-5 tenths off. If any of you have any recommendations, i'd be glad to hear them. I read a thread on another forum about how sometimes the strips often read .3 too low at mash temps (meaning that my 5.0 is really 5.3) but i'm not sure.

heres' my water profile:

calcium: 22ppm
magnesium: 6ppm
bicarbonate: 54ppm
sulfate: 25ppm
sodium: 33ppm
chloride: 50ppm
pH: 7.4

if the 5.0 pH is correct, that means that i should have about 350ppm calcium (according to palmer's chart). Obviously the first thing i'm going to do is order a pH meter, but does anyone have a possible explanation for why my pH is so low?

 

[bob352]

My guess, a pH meter will give a value closer to 5.7.
Or maybe the water does not match your water profile.
Seasonal variations are possible or your utility switched a source.
You could repeat your test with some RO water from the grocery store.

The rule of thumb I have heard (and follow) is always measure pH
with cooled wort and always assume mash pH numbers given are for cooled
wort unless noted otherwise.

Life is easier with a pH meter if you are going to try to manage the mash pH.