Seghier your geometry is all messed up due to overlapping poly's, you need to model transparent objects as a continuous welded mesh. (watertight)
This test is using overlapping coloured glass blocks with varying nd's inside clear glass. I made it from an arch-viz floor, wrapped into a cylinder shape, the blocks have 45 degree fillets.
I ran out of Nested priorities needed to add the water geometry. 11 is not enough in this case, due to the way I split up the colours, (I didnt want any adjacent blocks of exactly the same same colour/priority)
Dear devs, can we have 20 priority levels please.
10min render sl14