I remember seeing a lot of chatter about this, either here or on the other forum I frequent...
If I understand the problem correctly, many of the traditional poo pyramid solutions don't help
The inlet pipe lands on a shelf in the tank
... here's a picture I found online just to illustrate the idea... not the real tank in question, just something roughly similar....
So the flush lands on the shelf, with the water quickly running into the lower portion, forcing pyramid construction up out of the water.
The only thing I remember seeing was that some folks were installing tank rinsing jets positioned to wash this area down regularly.
My thought is to plumb the rinse jet to flow with every flush. Might help a little but not likely the real solution....
Too bad you can't get access in there to install a little ramp or wedge to that area.....would reduce overall capacity a bit but that might be a worthy tradeoff....or a pipe extension to direct the flow of the flush...
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