Need Help with Programmable Logic Using Stream Pump

[Dr. Jim]

I would like my DC skimmer pump to slow down when the pH rises above 8.25 (because I have a CO2 scrubber in-line to the skimmer).

In Programmable Logic, I set PG 27 to:
-Input 1= Stream Pump 1
-Input 2: pH value-1 Control downwards; Inverted

-Under Stream Group 1, Stream pump 1 (the skimmer pump) is set for: Min-10%; Max-70%.
-pH Value-1 is set at 8.25

What happens is that when the pH is above 8.25 (plus hysteresis) the skimmer shuts OFF completely instead of slowing down to 10%.

Any ideas?
Thanks!

 

[Gaël]

Something missing in your explanation, the skimmer is plugged into a powerbar? What is the function set on the 10v skimmer output?
For me it's a dead end, it is not possible to use a logic function on a 10v output.

 

[Dr. Jim]

Something missing in your explanation, the skimmer is plugged into a powerbar? What is the function set on the 10v skimmer output?
For me it's a dead end, it is not possible to use a logic function on a 10v output.

Yes, the skimmer is plugged into the powerbar.
Function is "Stream pump 1"; Min 1v - max 10v; Interface is L1
Does this give enough info?

 

[Gaël]

The output L1 is then only the output of the stream pump 1, the programmable logic has no influence on this output. You cannot set L1 on a programmable logic, only switching channel (socket of the power bar) can be set on a programmable logic (or another programmable logic). Sorry.

 

[Dr. Jim]

So basically, the way I have it set is correct for shutting OFF the skimmer when the pH rises above the set point..... (even though that isn't exactly what I wanted). I guess if I keep it this way I will have to settle for it being off completely instead of just slowing down.)

Not a GHL issue, but just for interest sake: But, actually, a better plan will be to buy a solenoid to close down the skimmer air input with the scrubber. (There are two air tubes going to the skimmer, so at least the "non-scrubber line" will continue to feed the skimmer if I use the solenoid to shut down the air tube with the scrubber. This way the skimmer won't have to be turned off).

Thanks for helping.