Funny, haven't been by Apug in about a month, and then the morning I think to stop in there's this thread.
That old thread is worth reading, but I was still working through a few issues, one in particular I had trouble solving when I added to that discussion...so I was less than concise. The problem is something I've since figured out...or had guidance from a Master in the field to figure out...I'll get back to that later.
Anyway, to update/recap: Hc-110 replenished, imo, is such an interesting developer. It doesn't do some thing things as well as other developers, but what it does well is really unlike anything I've ever been able to get elsewhere. At this point, all work on my site is done with it.
I began w/ a 3.5 gallon tank of 1+47 (Dil E) which I used for maybe a year. I found during the summer months, when it got hot in my darkroom (upper 80s), it was just too hard to keep stable though. With the amount of film I ran it was falling off in activity b/c of the heat. So I went to 1+31 (Dil B). It is much much more stable. I've not had a chance to let it sit in a hot degree darkroom for 2 weeks yet, but still, I've let it sit for 2 weeks otherwise and not seen any sort of drop in activity that can't be predicted. (After a few hundred rolls you really get to know the tank intimately, if you're paying attention) .
I replenish just like you would with a replenisher. I did the simple math to figure out how to do it from syrup. My current tank has maybe had 800 rolls through it and is remarkably stable - suprisingly so to me sometimes. I don't think it's necessary, but at 400 rolls I dumped off about 4 liters and put 4 liters of fresh in. I was processing film from an important shoot and did it for piece of mind.
The developer is a dark orange / brown sort of color. It's not black. But I only run TX really...some hp-5 and fp-4, but rarely. I've seen someone w/ a similar tank that was almost this dark navy blue color. I presumed he was running a lot of other films and not pre-soaking. I pre-soak.
As to your question about it dropping off, Jordan, I don't know why it would do that. The developer, as you probably know, will season and mellow out, but dying off it should not do. I use tap water filtered through a water board filter, but it's NYC water and may not be the same as yours. I don't know enough about water content and HC-110 and chemistry to know what could go wrong there...but anything is possible in the darkroom as far as problems. I'd ask what you're replenishing at, but you seem to have used the tank for long enough that if yo'd have been under replenishing it would have died long ago. Ditto for any mistreatment such as not covering it, or exposing it to a lot of heat... Other contamination could also be possible. Bottom line is, I've never seen what you're seeing, and don't know why it would happen. My tanks have always been stable...or as stable relative to how consistent I am with them. With that, if it's stressing you out, dump it and start new. Order 100 sheets of cheap 8x10 xray and run them through it to get it started on the seasoning process (they're double sided so 100 sheets is actually 200 I think).
Replenishing is in my mind extremely simple with HC-110, but b/c it's not sanctioned w/ a proper "replenisher" any longer there is a certain feeling it out opposed to exact science and test strips. Regardless, even feeling it out, I'm not a rocket scientist in the darkroom and my tanks always delivered if I've done my part.
Finally, the problem I had that I mentioned earlier and in the last thread that was linked here was streaking, a very specific and odd sort of streaking that ran down the length of the film. The odd part is that it only happens w/ Tri-x in deep tanks. It's something w/ replenished HC-110 and the new Tri-x base...combined w/ deep tanks and reel and rack agitation. I'd never seen anything like it and it drove me nuts. It took me a year or so to figure this one out. The guy who turned me on to HC-110 finally showed me how to get rid of it through a modified agitation and processing method in the deep tanks...a bit slower but still way better than daylight tanks for me. It's a different conversation though. And frankly, I'm not even sure I could explain it in writing since it's a specific agitation movement. But if you're not using TX or deep tanks you've probably not seen this.
Hope this stuff helps.