I'll take a crack at answering some of these questions. Someone please correct my mistakes or any misinformation I may be giving.
The Chart that Doug linked to above offers a comparison of all available controllers. Here is a direct link to it:
http://www.aquariumcontrollers.com/a...ontrollerchart
When I was researching if I should get a controller and which to get I listed these reasons for the purchase:
1. Control Lighting schedule (day, dawn/dusk and night and fuge light)
2. Control Heater/Chiller
3. Control Auto Feeder
4. Control Pumps (AquaSurf for Tunze)
5. Chart pH and Temps
6. Auto shut-off of pumps during feedings
7. Control Dosing
8. Periodically stir Kalkwasser
9. Control fans to prevent overheating in summer
10. ????
Regarding the DO probe, here is a thread discussing it:
http://archive.reefcentral.com/forum...readid=1258153
2 pH probes are required for your Controller to properly control adding any high pH effluent (Ca Reactor?).
ORP is required when using Ozone (I think).
Conductivity? no idea.
The AC Jr was the best bang for the buck in my research. It can only control 12 outlets. the AC and AC Pro can be accessed via internet, which would be sweet! The AquaSurf is Neptune's version of the Tunze Multicontroller. Not sure of any differences between the two.
HTH.
Kevin, How much of a Deposit is required?