The Fluid Interface is the same as an Interface but for fluids.
It has 2 internal tanks, one for input and one for output.
The Fluid Interface has an input slot to import the contents of fluid containers (like a filled bucket).
You can also interact with the input tank by using pipes from other mods.
Click a fluid container (like a filled bucket) in the "Out" slot to configure the output fluid.
Use left or right click on the fluid to change the mB amount.
Use shift to clear the fluid slot.
You can also interact with the output tank by using pipes from other mods.