This is probably a really stupid question. I have a M1 Ultra with the Safety Pro AP2 attached.

All the user diagrams show just connecting the original white pipe from the back of the M1 Ultra straight into the back of the AP2.

What it doesn't say is whether you leave the little circular filter in that original tubing. It seems counter intuitive to me to leave that there when the whole point of the AP2 is to have a prefilter installed in tha.

Does anyone know whether to remove the small filter or leave it.

Thanks.