well, it just depends on the replenisher's makeup. If you're using basically the same stuff you start off the fresh tank with--which sounds like that's the case?--then it should be really next to impossible to over-replenish the working developer. But, if you use a developer like D76 and D76R, this isn't the case, since D76R is lacking in restrainer. D76 is real fussy & tempermental when it comes to replenishment because it can get all out of whack and the pH can be screwed up as well.
Originally Posted by k_jupiter
the s.o.p. with repl. developers has always been to toss the working tank out when the amount of repl. added equals the original working volume. In practice, you either take out the amount you add--or replace the carryover amount. You really try to use as little as possible to keep the activity up. The time when you'd have to use more, is really when you're not running enough film through it or using it everyday.
With TMAX RS--I change out the tank every 4-6 weeks completely. This gives me a chance to clean the bromide sludge off the tank. When you start up a new tank--it's as John says above in his post, you have 2 options--you either start fresh, the film runs hot by about 10% and then slowly declines to lose maybe a third to half stop and levels off. At this point---the tank is seasoned--you start replenishing. At work, we usually run test rolls or scrap film through it to chew it up. Or, we just pull 10%. At any rate, it will run hot--then it will fall off in activity and this is where you want to be. This is very similar to the way E6 works as well.
The second option would be to use a starter to pre-season the tank. TMAX RS uses First Dev E6 starter for example. By taking a 1/3 of the working tank out & adding fresh--you would be doing something similar. Basically adding back in the byproducts--bromide, oxidised developer etc.--to get your new tank into a steady state. I ran a small one-gallon tank of XTOL like this for about a year and a half. But I had to agressively repl at almost twice the rec. volumes because I wasn't using it enough to keep the activity up. Just like E6 again--the key is in how often & how much you use it.
You can monitor it a couple of ways. Easiest is just to eyeball your negs & prints if you know what to look for. You could adjust the rate up & down based on the contrast of the negs and what it takes to get a normal print. The other way is to use b&w control strips. I do this off & on with kodak strips. Kodak's process control system is more like E6 really--but you could use Ilford's system more readily.
With Ilford--you do three runs of strips and average the densities of the plots to get your aims. Whereas, Kodak gives you starting aims to work back against (like E6). You will never be able to get a run to match completely from one to the next. It's the nature of the beast really--a happy process is one that drifts around a bit in the plots (within the tolerances). Once you get the aimpoints for your process--you should be able to run the strips at whatever intervals you decide. Maybe weekly, or before each run--I dunno, it's up to you really. This way, you'd have a standard to work against. The strips are used for more than tracking the CI--you can monitor the fix as well, and there's a concept of "speed" that isn't the same as film speed. It's the speed of the working developer basically. The process activity. You can also use them to figure out starting points for other film types.
One thing i do alot of, instead of running control strips all the time--is to shoot grayscales in with my studio stuff. I understand this probably isn't too practical for everyday shooting--but anyways, with a densitometer I can measure the density range of the neg and get an idea how the process is running. Really not too far off a control strip, although you don't have that level of consistency that you do from a frozen box of strips.
fwiw--I have never used them, but Ilford strips are on FP4. Kodak is TMY stock, and you apply a correction factor from the strip for other types of film.You could also make your own that would probably do a good enough job. As long as you exposed them all at the same time, and kept them frozen until needed. In my experience though--control strips would be necessary for a developer like D76, but if you use the same stuff--you can eyeball the quality pretty well.
Hope this makes sense.