you're kind of right dude.
however, just get the controller from neptunesys and get the modules locally.
they are available from those home automation providers
if you're looking at that to monitor temp and ph for certain actions such as
- turn off lights if temp > 28deg
- co2 injection if ph > 8.4
etc...
this is one of the cheapest and neatest solution.
however, if you're considering, do take note that each appliance module (chiller, lights) would probably set u at ard $60
cheers