Dvdck, I had the same experience!
I was surprised how high the Bathmate’s vacuum was, no wonder they don’t recommend pumping for more than 20 minutes.
When I first tried hydropumping with my Thickwall cylinder, I barely experienced any expansion until I pumped to beyond 6 Hg. I have to say, it was much more comfortable than my Bathmate but after 30 minutes (3 x 10 minutes) of pumping like this, I didn’t get the usual temporary expansion. I suppose if you can maintain a strong erection for most of that time it might help but that’s difficult in a bathroom without much sexual stimulus.
Those that have had success with water pumping, recommend long duration with low pressure. It sounds like ADS for girth - keeping your penis artificially expanded for as long as comfortable. I suppose wearing a cockring afterwards continues the work. After researching ADS, it seems that you need to apply the minimum tension that will cause the body to generate new cells to reduce the tension, this process is very slow so many hours of wearing ADS achieves best results. Hydropumping will probably reduce the time necessary to get the same results as normal vacuum pumping because of the physics but when you’re used to intense workouts it doesn’t feel like it’ll work. However if you apply the same logic as ADS it should, you just need to find that vacuum pressure/time sweet spot to get best results. Higher vacuums above 4Hg/in will cause problems such as blood spotting, edema, blisters and discoloration (it took me 1 year of no pumping for that to disappear). Long durations at these pressures will give you extreme edema that allows you to pack the cylinder but this thread is about targeting the expansion of the tunica, not the outer skin
capernicus1 suggested I do longer sessions - 45 minutes at 3-4 Hg/in. I’ll give that a go this evening. I usually add Epsom salts to my bath water so that’ll give me longer to absorb the magnesium.
To answer your question, Vacuum pump connectors are standard wherever you buy them so you shouldn’t have any compatibility issues.