Acroholic;901027 wrote: Yes, the SL1 pH probe should be in the calcium reactor probe port. Use the separate monitor to just look at system pH.
An example of when you would want a second SL1 or SL2 module with a pH probe tied into your RKL/RKE system would be if wanted to control a PC4 outlet tied to a kalk reactor or the like. In this case, the pH probe would function mainly as a system pH monitor, but also have the ability to turn off an ATO running through a kalk stirrer. For example, you program the ATO's PC4 outlet to turn off the ATO outlet if the system pH goes above 8.5 or so, which could happen in the case of a leak that caused the ATO to run continuous water through the kalk stirrer.
When you start getting into equipment like calcium reactors, you are probably getting to the limit of your RKE's 4 module capacity, and should consider moving to an RKE Head Unit.
That was my path. I started out with RKLs, then had to go to RKEs on both my reef tanks as the equipment list grew.
I still have those two PC4s I bought from you. If you need one back, just LMK.