Did you connect the ground wire on the 0-10V port to the ground of the pump? Otherwise they are operating with potentially isolated grounds. I would suggest putting a meter on the +0-10V output after you connect the ground and before you hook it to the VA line just to make sure that the reading is in range.
Also you are disconnecting the VA line from the Chinese controller or running without it entirely? If you are simply trying to connect to the VA line with it still hooked to the Chinese controller, you will not be successful.
The Apex 0-10V *should* work as the RA is already able to control it with its 0-10V output.
Dennis
Sorry, I think I missed the details on how to control this pump on 0-10 v analog.
I have an iks aquastar with simmod 0-10v analog controller. Would love to be able to control my coming wp40 with that.
Any diagrams on how I should wire this?