I had no luck with Amazon and ended up getting everything from Lowes.
Everything seems to be working as it should except I need to crank the filter housing a bit tighter (gonna need wrenches, as it's already as tight as I could get it by hand), it's leaking about one drop of water per hour right now, which isn't a big deal, but I'm not comfortable with any leak, really.
The other thing is that I don't think it's getting enough water flowing through it. It's on the output of my Eheim 2226, and a pocket of CO2 is forming at the top of the reactor. No bubbles are driven even a third of the way down the filter housing. It's acting like more of a bell than a reactor. Guess I just need a stronger pump?
#1 - DON'T CRANK THAT CAP DOWN!!!
You can crack them EASILY by over tightening them. A wrench is a good idea to get because once they seat they're a bltch to get off again, and unless you got another strong guy to hold it while you twist, you're not gonna have a good time. If you go onto the DIY house repair forums you'll learn that this is a major gripe about whole house filter systems. Beware.
#2 - APPLY VASELINE!! Put COPIOUS amounts on the flat rim where the cap touches the base, and also on the O-ring all the way around. Put some on the threads too. This will help reduce the friction and get that seal to work. You shouldn't have leakage. Is your downpipe touching the floor of the base and keeping the O-ring from seating? If so you might want to trim it up a bit. In any case, keep in mind that some day you're going to want to get that base off and things you do now will greatly facilitate it.
I run a Supreme Mag 7 on mine, and I back it off with a ball valve a bit, but not much. There's plenty of flow. I also bought some dollar store pot scrubbies that have handles and removed the plastic mesh and used them around the downpipe.
<---- Unscrew the center piece and a perfect little ring of scrubbie is presented for your downpipe!
You can see one of them here:
No judging!! I was in the process of securing all that spaghetti!