Jobo 2500 Tanks - Ribbed Inside?

I've just bought a Jobo 2523 tank. It has a ribbed surface on the inside. I though it was the 2800 paper tanks that had ribbing to allow chemicals to reach the back of the sheet? Is it supposed to be there in the film tanks? What purpose does it serve? Or have I been sold a 2800 tank instead?

I dunno. I have both with- and without-ribbing, and they both work great for both film and paper.

My 2521 tank has ribs. Not sure why. I only ever use it for inversion processing with the 2509n 4x5 reel.

Jonathan

the only 2500 system tank with no ribs is 2550 (which is the only one that does not double up in print use).

all other 2500 system tanks also double up as 2800 system tanks with other labels, no core and chemical beaker light baffle.

multitank 2 (2523) = testdrum 2820....