Thanks, but I've been those routes.
I want a bottle of approximately 2.75-litres capacity. My home made processing tanks will hold eight rolls of 35mm film, or five rolls of 120 film, which both require about 2.6-litres of solution. I want the bottle to be full to the brim.
I have tried adding marbles to a 4-litre jug of D-23, and it's a real drag when the bottom of the bottle slowly accumulates a sulfite sludge. The marbles rattle when I invert the bottle to mix the replenisher, and they are heavy. It takes almost 100 marbles to displace 1-litre, anyway. And, I only have one glass bottle; plastic bottles will flex too much, and they get much, much too heavy with those 100 marbles.
Using two or more bottles is a non-starter, as one must constantly mix them in a bigger container before and after use. Spillage becomes a problem.
Why don't I just mix 4-litres? Because I am trying to keep the volume down to the minimum to cover the reels of film. I mix my replenisher one or one-half litre at a time. When I have added a volume of replenisher equal to the volume of developer, I use it to capacity, then sewer it.
I have had a bottle of D-23 on the go for almost three years, and it still works just fine. I have about 500-mL of replenisher to go before I mix another litre. When that's gone, it will be the end of the line for that developer.
So, rather than trying to correct what is perceived as the error of my ways, would anybody have any real information (a.k.a. facts) about my question? I have been photographing for almost 40 years, and have probably made any mistake that can be made, at least three times.