Thanks, SJ!
Well, I did it.
I opened the drain faucet (and it really is just that: a faucet like you would see on the side of your house) and vacuumed and my filter pressure does not appear to have gone up at all, so maybe most of the waste went out of the line.
I really hope so because I just brushed down the walls again and I will definitely have to repeat this whole process tomorrow!
Thanks again,