Some opinions on pH adjustment

[Asator]

So I just got back from my LHBS where I picked up some pH test strips. I took a sample out of the carboy and did some readings. Here's what I got:

SG: 1.080
Temp: 67
pH: between 3.2 and 3.6

The test strips come with that little sheet used to compare the color of the strip to, and with my strip the color was somewhere between 3.2 and 3.6. So I'm checking out Ken Schramm's books and he recommends trying to adjust the pH upwards if your pH goes below 3.5. Well, since I don't have a very precise reading I could be below 3.5 or I could be right at it.

My question is this, if you were me, would you, a) do like Ken suggests, and add CaCO3 a little at a time and try to raise it up to 3.8, or would you b) wait it out a few days, check it again and if it's lowered even more, fix it then?

My gut is telling me to wait, but I figured it would be best to ask.

Thanks,
A

[wayneb]

I'd go with your gut in this case. Partly because we've learned more about yeast pH tolerance after Ken's book was published (and a pH of 3.4 is usually more than high enough to support robust fermentation), and also because I wouldn't want to push pH too many times during the course of a fermentation. I'd also recommend using potassium carbonate (or potassium bicarb) instead of CaCO3, since calcium carbonate takes much longer to react with the acids in the must, so your change in pH can take a while. That makes adjusting to a desired target value much harder than if you get a more rapid change when you add the chemical.

One other thing to check is the reactivity of your pH strips. Those things are notorious for losing sensitivity if they have been stored in air for long periods of time. Check the lot that you have by dipping one strip alternately into white vinegar (which should skew the color immediately to the shade corresponding to the lowest value), and then into a solution of 1 tsp of baking soda dissolved in a cup of water (which should change the shade to the highest value). If you don't see the color change over its entire range, or if the change takes a relatively long time (say it doesn't react within a few seconds), then throw out your strips - they're expired.