Recently my pH meter, which is a pHep® 3 pocket sized microprocessor pH meter, a Hanna Instruments company product, needed new batteries. Normally this wouldnt be a problem, except the specified batteries are 4 x 1.4 V alkaline batteries, which appear to be not available in this country any more. Or at least I couldn't find them when I looked around. Thinking laterally, I reasoned that batteries would over the course of time drop; therefore the meter has the ability to operate over a range of voltage. In fact, the unit tells me when the batteries are too low to work and need replacing. The closest voltage I could get is 1.5 V so I loaded them in and then proceeded to calibrate in an initial buffer solution of pH 7 as per normal. Calibrating to an alkaline buffer solution of pH 10, I checked my freshly mixed C41 developer solution. After years of mixing this solution up, I know pretty much exactly what the initial pH of this solution comes out at, before I adjust for final pH. The reading was within 0.1 pH of what I would expect, I was pleased. Whilst this was satisfactory and the subsequent film I developed, appears to be alright, I wonder if anyone can give me an idea of just how much significance the battery voltage can be, or is, with this kind of instrument? The supplier of the product in this country wasnt too sure whether or not the voltage difference would be a problem, not really a great help. When I print the negs, I will have a much clearer idea of anything awry! Mick.