Replenish TF-4?

I use LPD and TF-4 in a Nova slot processor, and have been "topping off" the LPD for a couple of months with no problems or loss of activity. Can i do the same with the TF-4? I've just been periodically emptying it and refilling, but I'd like to be as efficient as possible. Thanks.

You must test the fixer for Silver build up. There is a standard test that can be bought from most suppliers. It is basically a Potassium Iodide solution. If it turns dark yellow and a heavy precipitate forms, you must discard the fixer, but the best test is to see if the time to clear film has exceeded a certain value and that you are giving the film enough fix time.

The same goes for paper, but you have to use film for the clearing test, as the film is easier to see as it clears.

PE