A gentleman from my LFS where I purchased the Aquarium installed the return pump. I would have definitely used hot water myself as it can make a huge difference - like a hot knife through butter lol. I used hot water when connecting the barbs on my Aqua UV sterilizer to the hose as well as the pump connection for the sterilizer. Boiled some water, poured it into a coffee cup, dipped the hose for maybe 10 seconds or so, then made the attachment. I've also used the hot water trick many times when setting up a drip system for our garden and yard. That being said, our LFS guy didn't use hot water, and muscled it and struggled for a while. I offered hot water a couple of times, but my offer was refused lol. So, while I didn't personally do that connection I'm guessing it would have been easy peasy with a little hot H2O, or at least a lot easier.