I made one of these reactors at the first of the week and was impressed with it. I did go with Gatekeeper's suggestion of an inline tee instead of drilling into the housing. It was easy to put together and it actually increased the flow out of the canister. I used it for a day and then decided to try using my canister as a reactor with the inline tee on the input side of my filter. It's working well too and I'm sticking with that at least for now.
I said all that just to say if you're wanting to try an inline reactor then give this a try instead of a PVC reactor. It was very easy to set up and pretty efficient along with maintaining better flow, at least for me.