Originally Posted by Chappy
Screw 1st tank in slowly until it starts to hiss, then back it out so it seals again. Then screw in the other tank. Then screw 1st tank all the way in.
I've used this method for many years on my old VM, as well as MegaZ.
Never had a problem, except for one oddball ASA that had an extra long pin. As long as the valve oring seats BEFORE contact with the pin, this method is easy.
I ran my VM on dual siphons before, though I not sure it matters, as long as you are consistent (ie all siphons, or all non-siphons).
Note, regardless of what tank you are using, just make sure you do the screwing, and unscrewing with the valve oriented so liquid does NOT entered. This will make sure the oring does not get sliced in the process.