It is the ratio that is important here, you need to create the right strength of solution, it is not not 250ml specifically. I actually did the math originally to get the numbers for a full liter but in my Nikor tanks, 250ml covers one roll, 500-2, 750-3, so I just use/kept those numbers.
The place where 250ml is important is that it is the smallest amount of the normal working solution needed to develop a 36 exposure roll of 135 or 1 roll of 120.
Much depends on your tank but your number sounds too high. The tank does not need to be full. In fact I purposefully leave at least one reel out and only fill the tank enough to cover the reels. This leaves a significant air space at the top which I think helps the replenished bleach work better, it needs aeration. Given that the developer is typically mixed moments before use and then immediately discarded, maybe 15-minutes total exposure, the air doesn't have time to affect it.
To find your real numbers throw a reel in your tank and then fill until the reel is just covered/submerged, dump this into a graduate, remember that number; that is the minimum amount of chemicals I would use.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Anaïs Nin
Hi...I haven't ordered mine as yet but it will be about $120 for one kit and starter coming from Liberty Photo in Minneapolis being shipped to my Oregon West Coast address. And yes, it is a separate bleach and fix not a blix and that's one of the reasons I'm going with Trebla. The other is just because I can't find anywhere where I can easily buy everything Kodak C-41 I need in reasonable quantities (for my volume of film) without jumping through ungodly hoops.