I have a few questions about fixer (both C-41 and black and white). I'm posting here because it seems a bit more focused around C-41 fixer.
1) On the black and white side, I'm using Kodafix sort of accidentally, but I've got a bunch of it left, so I figured I'd keep using it until I run out. According to the bottle, the capacity is 20 rolls of 135-36 per quart if you use a stop bath (which I do), but I seem to get about 12-14 rolls pretty consistently using a hypo-check. With the latest batch of fixer, I did 12 rolls of Tri-X (all EI 320 or 400) over 2 months. I was developing rolls 13 and 14 (in this case, P3200 at EI 3200) and the fixer tested bad before I fixed. I fixed anyway and just added some time.
My question here is is this normal, i.e. is the difference in capacity between what the bottle says and what hypo check says usually that drastic?
2) On the C-41 side, I use the Rollei kit which has a separate bleach and fixer. According to those instructions, 500ml of fixer can handle 10-14 rolls of 135-36. Is that realistic given my experiences with black and white? I know the fixers and films are different, but I'm curious why the I should trust the C-41 numbers when the black and white numbers are so far off. Does hypo check work for C-41 fixer?
3) How similar are the two fixers? Note: I'm *not* wanting to use the two interchangeably, I know that doesn't work, I'm just curious about the differences in the process/chemistry. The MSDS for Kodafix list ammonium thiosulfate as the primary ingredient. The MSDS for the Rollei fixer lists both ammonium thiosulfate and dinatriumdisulfit (my German isn't good enough to know what that actually is).
4) Generally, can I combine the two fixers for purposes of disposal? I know that may have something to do with local regulations, but when I take bottles to the hazardous waste disposal place, do I need to separate them. Ultimately, I think the thing they care about is the silver and that's not going to be different between the two (I think). Of course, if they're just pouring it down the drain it probably doesn't matter :-).
Thanks in advance, this is just something I've been wondering about.