What is the advantage (if any) of having the downstem as low to the base of the tube as possible? I have a HiSi U-Perc and I broke the downstem a few days ago cleaning it, so I went to my lhs to replace it. I went with the Alex K showerhead. I think it's really nice and definitely an upgrade of the stock HiSi diffuser that came with it. They had them in 1/4 increments. He measured my old downstem and pulled out the appropriate Alex K and we took a look at it. There was room for the next size up (5 3/4) so we tried that one out and it fit perfect, barely off the bottom of the base. So my question is does it make much of a difference? Do water levels effect the quality/amount of smoke?