GHL Kh dosing based on Ph level

[Whitearmy61]

Looking for help and confirmation on this one,

I've used programmable logic, switch channels and virtual dosers to set up my kh dosing based on the ph value as I am using two part 1 solutions, RZ complete and RZ ph plus. I've set the ph nominal value to 8.3 and hysterisis to 0.1

So far the ph plus is dosing as ph value is around 8.2 and I'm expecting the complete to dose once I hit the 8.35 and above mark, however my question is what will happen if ph hits the upper switch point of 8.4? Will the complete part 1 still dose or will neither dose as ph is above the upper switching point?

If i've missed anything in the initial setup please let me know.

 

[Pod_01]

I did something like this while back, I just don’t remember all the details.

I used this as a guide:

How to stop dosing when pH is above (x) - GHL Advanced Technology

www.aquariumcomputer.com

Hope it helps,

Good luck,

 

[Whitearmy61]

I did something like this while back, I just don’t remember all the details.

I used this as a guide:

How to stop dosing when pH is above (x) - GHL Advanced Technology

www.aquariumcomputer.com

Hope it helps,

Good luck,

Thanks for that, I used it to setup the programming side of it for the two dosers but was just wondering what happens if the Ph goes over the higher switching point really.

 

[ReneReef]

It depends on how you exactly implemented the two logic statements.

Mine are like this:

If I use your set point and hysteresis the following would happen:
pH plus dosing starts when a pH below 8.25 is reached and then continues until a pH of 8.3 is reached.
RZ complete starts when 8.3 is reached and continues as long as the pH is above 8.25.

 

[Whitearmy61]

It depends on how you exactly implemented the two logic statements.

Mine are like this:

If I use your set point and hysteresis the following would happen:
pH plus dosing starts when a pH below 8.25 is reached and then continues until a pH of 8.3 is reached.
RZ complete starts when 8.3 is reached and continues as long as the pH is above 8.25.

Thank you, so I've not set both to "control upwards" with one set to invert. I've set mine to "increase" and the second doser to "decrease". Should I change that? If your ph was to rise above the highest set point would it continue to dose complete regardless of ph value unless it fell below 8.3?

 

[Pod_01]

Thanks for that, I used it to setup the programming side of it for the two dosers but was just wondering what happens if the Ph goes over the higher switching point really.

I had it set up long ago, so going by memory. I used that that guide so one pump would react. The other pump was set on inverse, so if pump one was not dosing the pump 2 would dose.

I also used virtual dosing pumps to test the program before going live.

Hope that helps,

 

[ReneReef]

Thank you, so I've not set both to "control upwards" with one set to invert. I've set mine to "increase" and the second doser to "decrease". Should I change that? If your ph was to rise above the highest set point would it continue to dose complete regardless of ph value unless it fell below 8.3?

Correct.

Because what will happen in your current situation:
pH plus will be dosed to a pH of 8.3. Then it stops, and the RZ complete will only kick in when a pH of 8.35 is reached.
The complete will be dosed until the pH hits 8.3 again. Then it stops and the pH plus kicks in again at a pH of 8.25.

In between pH plus and RZ complete there will be periods where nothing is dosed. The inverting trick prevents that.

 

[Whitearmy61]

Correct.

Because what will happen in your current situation:
pH plus will be dosed to a pH of 8.3. Then it stops, and the RZ complete will only kick in when a pH of 8.35 is reached.
The complete will be dosed until the pH hits 8.3 again. Then it stops and the pH plus kicks in again at a pH of 8.25.

In between pH plus and RZ complete there will be periods where nothing is dosed. The inverting trick prevents that.

Got it, thank you!