D-76 economically?

I'm an old D-76 fan. It works best diluted 1 + 1 as a one-shot. It is also quite cheap that way (as noted above). You should store D-76 undiluted (the diluted solution doesn't last long), and then dilute just enough to make what you need for your current developing session. A half-full bottle of D-76 has a rated life of 2 months (6 months for a full bottle), but will probably last a bit longer. Developing single rolls in a half liter tank, you get 4 rolls per liter or about 16 rolls per gallon. You can use D-76 undiluted. It gives somewhat smoother grain and somewhat less sharpness than the diluted variation. The capacity is about the same, 16 rolls per gallon, but you can extend the life by replenishment with D-76R. D-76R is no longer available from Kodak, but it is easy to make, and you might find some other source. This only makes sense if you have sufficient volume to use it up before it expires.

Replenishing can work but you must be using the solution on a regular basis. You must also filter the solution periodically and run test strips. Just letting it sit can result in ruining important photos. Don't ask me how I know about that.

I find that Ilford Microphen works well at full strength and with re-use. You add 10% to the time after each 36 exp or 120 roll and keep it to the recommended 8 rills per Quart or Liter. I filter the working solution as I pour it back into the bottle. With some films using D-76 1:1 will increase grain and sharpness. With other film (T-Max, Delta) the results seem better with with undiluted D-76. If you are in the U.S. you can look at the Freestyle website and try a gallon of powdered Arista brand D-76 equivalent/replacement. Some of these "76" type developers actually use phenidone, like Microphen, and not metol, like D-76 but are economical and work well.

Ditto Replenished developers work best when they are used on a regular basis. If you develop film occasionally then they are not a good choice.

What about HC110?

4 fresh oz are required for 80 sq inches of film plus water to make up 8 oz, ie one 36 exp roll. So NO. Do not try.

Use full strength and replenish, but you need proper test strips and densitometer readings to be sure the developer is correct activity. Or just fly by seat of your pants. There is two much work making the images involved to try it that way in my opinion. You will need to mix your own replenisher.

Mix your own D76 from scratch like I do and you will save a ton of money and you can do a liter at a time. Metol and Hydroquinone from Photographers formulary, sodium sulfite from"The Chemistry Store", borax from the laundry aisle ( 20 mule team is fine.} Done this way, the savings are hugh and you always have fresh developer.

4 fresh oz are required for 80 sq inches of film plus water to make up 8 oz, ie one 36 exp roll. So NO. Do not try.

Use full strength and replenish, but you need proper test strips and densitometer readings to be sure the developer is correct activity. Or just fly by seat of your pants. There is two much work making the images involved to try it that way in my opinion. You will need to mix your own replenisher.

Mix your own D76 from scratch like I do and you will save a ton of money and you can do a liter at a time. Metol and Hydroquinone from Photographers formulary, sodium sulfite from"The Chemistry Store", borax from the laundry aisle ( 20 mule team is fine.} Done this way, the savings are hugh and you always have fresh developer.