Re: Potentially stupid pt/pd question
People usually think that replenishing is to add just fresh POTA solution. That is only one part of it. As Clay and others noted the developer should be acidic. Depending on the papers that you use the oxalic acid from the developer will be used faster or slower. Papers with carbonate buffer are notorious for depleting oxalic acid and changing pH of the developer very fast. If your papers are of that kind you might need to add acid more often.
ANd then some papers are just very difficult to clear and are more prone to stain all together. In practice it might be easier to change the paper then to mess with a chemistry a lot (not that it is not a good learning experience).
Here is my work flow/clearing
I develop in POTA, room temperature (always 80F in Houston) for about 3 to 5 minutes, perhaps longer then normal, but I found it helps with clearing. Then I soak in a small amount of fresh tap water (say 0.5 liter to a liter in a tray for 8x10 print) for another 5 to 10 minutes. I do not like running a lot of fresh water through the print coming out of the developer as it inhibits clearing in my practice. After that the print goes into a clearing bath that hase some sodium ETDA (heaping teaspoon) and citric acid (same amount) per liter. Ten to 20 prints culd be cleared in this bath. I mix that fresh for each printing session.