Joe used the same pump in some of his tests...
It looks like he used a pressure fitting, on the inlet.
I'm googled out: what's the plastic on the housing of the HydroThruster 500? Is it an acrylic, or a polypropylene? Can't pick a glue without the info...but could try a few: Devcon's "Plastic Welder", superglue, PVC primer and cement (probably not) or our ole'time favorite: Goop! (but I prefer to keep that for sealing leaks).
Otherwise, Joe's "mechanical" joint will work well.