GHL Profilux Salinity Hysteresis

[clawhammer]

Hi All,
My salinity dropped from 34.6 mS/cm (1.026 sg) to 47.1 mS/cm (1.0228 sg) without any alarm. Nominal value was set to 53.0 mS and hysteresis was set to 10 mS.
Under the Alarm heading, "Active" is switched on and "Max. deviation +/-" is set to 5.0 mS.
I've calculated that hysteresis should be set lower at 1.5 so it alarms below 1.025 and above 1.027.
Does this sound correct and are my other settings right? Is there anything I'm missing or missunderstanding?
TIA,
CH

 

[clawhammer]

Just in case anybody reads this....

So I figured out that hysteresis is a switching point rather than alarm activation. It could be used to control salinity. For instance, if you had salted water that's dosed to increase salinity then you would select the point at which you want that salt water dose to kick in. So if your nominal value is 53mS (1.026sg) and you want to dose salt water to increase salinity if it drops to 52mS then you would set hysteresis to 1. It's to prevent constant activation of a function.

This is good to know as I need to find a solution to increase my constantly dropping salinity due to test water being removed for the Kh and ION D's.

To achieve an alarm for my reduced salinity I need to change the "Max. deviation +/-" figure. It was set to 10 so I've now amended this to 2.5. This is the lowest figure it will allow me to put in there. This means it should warn me when salinity drops to 51.5mS (1.0246sg) so I can take remedial action before it falls so low again and until I've set up some kind of automated top up.

Interested to hear if anybody has set up an automated salinity top up using GHL equipment.

TIA,
CH

 

[EnterName]

Sorry I didn't catch your post earlier, but now you have seemed to solve the issue on your own :)

 

[clawhammer]

Sorry I didn't catch your post earlier, but now you have seemed to solve the issue on your own :)

Hi, thanks. Yeah, possibly resolved the issue of low salinity alarm. Will do some research on topping up with salt water to raise salinity as this will be an ongoing issue for me.

 

[BeanAnimal]

I’m don’t bother with automating it from sensor readings. I just set a dosing schedule to pump SW in every day to make up for testing. Even if it is not accurate, drift is berry slow and easily corrected once every month or three.

 

[ingchr1]

FYI, if you are able to use GCC it will give you the switching points.

 

[clawhammer]

FYI, if you are able to use GCC it will give you the switching points.

Thanks for this. I see what you're referring to at the bottom of the screenshot.

Is this generated automatically based on the hysteresis figure or have you entered manually?

Your nominal value is 53mS so with hysteresis of 1.0mS I'd expect switching points to be 52mS and 54mS. The figures shown seem to be for hysteresis of 1.5mS. Also, I'd have expected the alarm points to be 50.5mS and 55.5mS. Maybe GHL has built in an additional 0.5mS?

 

[ingchr1]

...Is this generated automatically based on the hysteresis figure or have you entered manually?

Automatically based upon the entered settings.

Two Position Controller:

A hysteresis of 1.0mS is +/-0.5mS from Nominal.

Control Upwards the outlet will switch On at 52.5mS and Off at 53.0mS.
Control Downwards the outlet will switch On at 53.5mS and Off at 53.0mS.

The Alarm is 2.5mS from the switch On points, 50.0mS and 56.0mS respectively.