A few things to note about the different mouthpiece setups with the minivap. The seal on the lid of the miniVAP is important for perforomance and as many people have noted, the silicone tubing tends to seal a little better than the mouthpiece, yet many people prefer using the mouthpiece. The miniVAP comes with silicon tubing and it also comes with a plastic mouthpiece. The user can determine which works best for him or her by trial and error, but both will work given that the the lid is secure sealing the top of the miniVAP. On some of the original earlier units there was a small plastic O-Ring between the lid of the minivap and the top of the filling chamber.
The most recent itteration has no O-Ring and it seals completely without the O-ring. The stem is a little bit longer on the most recent version. There is little real difference between these versions in terms of the seal but because the seal is very imporatnt for performance, there is some ongoing tinkering with that seal. We can on a case by case basis work with customers if they have any concerns about the mouthpieces and various systems used.
Most people use the silicone tubing and many peopel have developed adaptations already from using twist ties to tightening the seal on the silicone, and a couple have talked about a water attachment. Note that we don't have such an attachment at this time, but the point is that customers have already made adaptations on their own that we know about.
The key in all cases is to make sure the seal is good enough to mainatin the airflow. As the unit is broken-in over time, we find that the seal becomes tighter and tighter, so it is the initial uses that you have to be sure the mouthpiece is properly seated on the unit. When using the regular mouthpiece without the silicone tubing a lot of people rest their index finger on the stem which is a natural way to hold it, and helps maitain the seal.
It is also important to pack the chamber properly and to experiment with different ways of packing the bowl/chamber. Usually, you want ground material and you do not want to press the material down into the bowl hard because you need to maintain some airspace between the bottom screen and the material.
Also, the material can slightly overflow from the lower part of the chamber. The chamber is really not just the small cylinder part of the bowl, but also includes some of the upper portion of the chamber and top. So you really fill the chamber a little more than might be first obvious and you also don't pack it down hard.
As you inhale on the device the material will flow to the top and a space between the bottom screen and the material developes. This is necessary to maintain air flow. If you pack it tight and the material is pressing on the bottom and won't dislodge you will not have the right airflow.
Likewise there has to be a screen cup used when using oils or other materials. They should not press up against the bottom screen. The accessories include screen cups that can be used to create space. However, when using herbal materials of any kind, the best method is to grind the materials and simply tap it down very, very ligyhtly. It's even OK if the top presses down a bit on the material when you close it as long as you don't press it down with your finger into the bottom cyclider, which would be too tight for air flow under normal curcumstances.
The idea is to use your own trial and error, but remember that the seal and a bit of airspace is needed to get the right vaporization effectiveness with the miniVAP.