The other day I developed a roll of Tri-x (120) exposed at 320 and a roll of APX 100 (exposed at 80). I developed them in Pyrocat HD (1:1:100) for my usual time and temp. The negs ended up being quite thin. I put it down to having too many pints down at the local pub and underexposing as a result. Today however I developed another roll...this time HP5 (120) exposed at 200. The negs were even thinner than the others.
The Pyrocat solutions A and B were mixed perhaps 5 months ago and are now in half empty bottles (separately of course).
Is the developer losing potency?