Questions before I buy a calcium reactor.

[Delphinus]

I have never used a pH controller with my reactors as you can dial them in yourself, but if you want to use one it's a "nice to have." I tried dialing in a reactor though before having a pH monitor at least, and it was a nightmare. You need to make the setpoint 6.7 and test kits are going to be hard to get the resolution you need.

You can use a kalk reactor still. I try to use both kalkreactor and calcium reactor on my tank. The reactor pulls your tank pH down slightly, the kalk will help resist this.

Most calcium reactors don't need a feed pump. You can use a little powerhead though, or T off a sump return, or use gravity feed. There tend to be lots of options.