I see Reef-Pi builds all over the place, but is there a good DIY link, article, or thread of using a computer as an Aquarium Monitor/Controller? I have several basic laptops that can run Windows or Linux, and I also have a macbook. I've got a router that I could put DD-WRT on. I feel like I have access to all of the materials, but I just don't know where to start. I'd rather not use a Rasberry Pi, I'd much rather have a dedicated PC in a case to control and monitor everything.
Echoing what
@Michael Lane just said.
Raspberry Pi is a computer, the only difference is it exposes the physical pins which allow us to connect the sensors directly.
This is exactly the current limitation with Laptop/PC. The connectors are standard (for example usb or audio etc) and it will be some work to integrate individual sensors, control mechanism (Relays for example). But this is not impossible, one can use USB or wifi based sensors. Some of the atlasscientific probes have USB interface, they should be useful.
There are also some Intel as well as arm based more powerful computers (such as atomic pi, or the arm development boards from Samsung) that exposes the physical connectors and almost as powerful as desktop/laptop. They are way more expensive though.
Once you get familiar with how these things work, you;ll realize theres whole continuum of choices and not just two extremes. But solutions tailored for one hard to get working for the other boards, often time. And their relevant ecosystem may not be that big. So when you impose some pragmatism, the choices reduce.
BTW, reef-pi runs on windows and osx as well

, we use it for development. and with recent 3.0 features, if we do get wifi /usb based sensors , I dont see a lot of issues using a desktop pc or laptop as controller.