Salinity Programming

[ant]

I'm looking for a solution to allow me to keep a consistent salinity in my aquarium where water is skimmed out. As this is a nano, skimmer water can have a large effect on the salinity and I thought I'd put my GHL to good use.

I intend to use a T value on the input to my top-up dosing pump. One side of the T will go to the fresh water container and the other side with go to a salt water container via a solenoid. When there is no power to the solenoid, the gate will be blocked and only water will be taken from the fresh water container - when power is applied, there should be a mix applied to the tank so the salinity can be brought up to the correct value slowly.

So, I need some programming logic to say...

1. When the conductivity falls below "x" value (which can be the nominal value - hysteresis?) then turn on socket y
2. When the conductivity reaches the nominal value then turn off socket y.

Can you give me some ideas as to how I can do this?

[kidney514]

Don't need programmable logic for that!

Just set your socket Y to Conductivity increase, nothing more to it than that!

Unless you want to increase the salinity when the level is to low, then that would be another thing!

[ant]

Yeah, I want the solenoid to be powered when the salinity decreases and then powers off when it's back up a nominal level.

[kidney514]

Well then just set the socket to 'Conductivity 1 Increase' that will do it!

[ant]

Ta. Will give it a try.