PM1 or PM2?

[therman]

I'm trying to figure out how exactly to configure the Apex based controls for my two separate systems.

I'll have a standard Apex setup on one tank, and run a loooong Aquabus (equivalent) cable around 40ft to the sump of the other system. There I'll have a probe module and an EB8 at least to start. Trying to decide if I want to base it on the PM1 or the PM2.

I obviously want to track the temp of the second system. What I can't decide is if pH or conductivity would be more useful. It does have a reactor, but it is a DIY setup with no place to easily add a probe, and doesn't have a solenoid. I was thinking that the conductivity would be handy, as I could set it to turn off my auto-topoff if the salinity drops below a certain threshold. However from what I've read the conductivity probes can be pretty touchy, and they are rather pricey.

Any input, pros/cons would be appreciated.

Thanks!
Tim

 

[bazineta]

My personal experience with the salinity probe is that you need to clean and calibrate it from time to time (I do mine about every 60 days), but it otherwise seems to be quite solid.

I think the original instructions weren't all that clear about (a) if you're going to use temperature correction, then you must have a temperature probe attached to the PM2 and (b) during calibration, the calibration fluid must be at tank temperature. Seems to me that these two seemingly minor things tripped up a number of people. The new documentation is much better in this regard.