How to wire two spring reverb tanks with a pot?

Hi,
I would like to connect two spring reverb tanks in parallel and to add a pot that mix between the two tanks (like a pan pot on a mixing board).
Can someone please explain me how to wire the two tank and the pot?

To start with: I think it is a bad idea to connect a pot immediately after the reverb tank.
To get the best quality, you should not really load the reverb tank with a low(ish) impedance.
A better solution would be to amplify the return signal of the two reverb tanks, and combine/mix the signals after the amplifier stages. Assuming levels are (almost) equal, you could use a 10 K linear potentiometer, connect the signals to both sides of the pot and tap the signal to the amplifier from the slider contact. If the output impedances of the recovery amplifiers are relatively low, you can blend the signal with the potentiometer then.  The potentiometer itself (the slider) should not be heavily loaded. (An impedance of 30 K.ohm or higher is fine. A lower impedance will change the control behaviour.)