Need help with Aquarium Plant Regulator

[Macdaddynick1]

So i set up a calcium reactor using a master flex pump and an AP regulator. The pump is pulling the water through the reactor, so there is a negative pressure in the reactor.(technically positive but the chamber is not otherwise pressurized)

The problem I am having is that I set up the AP regulator but i am keeping it off for now. I tested the regulator it seems to be working but when its off it starts syphoning the water back into the tube.I have a cheap check valve on the line since i thought there was no need for a heavy duty CV because there wouldn't be any back syphoning .
It seems as if the pressure in the regulator itself drops and starts pulling the water back to the point where it collapses the check valve and lets some water in almost to the regulator itself.
Does anyone have an idea what might be causing this?

 

[Reefing Madness]

 

[reeferfoxx]

Your cheap check valve is the issue. When I was running my co2 planted tanks with a pH controller, I had the same issue. I bought a better metal check valve from CO2 Art and that issue stopped.

 

[Macdaddynick1]

thank you , I ordered two ss check valves, waiting for those to arrive.

 

[reeferfoxx]

thank you , I ordered two ss check valves, waiting for those to arrive.

You might have to change the pressure some. When I switched it was a little more difficult for the gas to pass through. Trust me though, you won't get any water sucking back up.