There is some trade off in size but the skimmer is very powerful, I have seen it with my own eyes. Making it bigger would defeat our goal of always having the most powerful- smallest- skimmers on the market. In large parts of Europe most equipment is used in tank so being small is a necessity. I would see no reason you couldn't buy the pump seperate but it may not work that well because of the plumbing it connects to, A few things I know is that you can almost double air in take by the length of the jet tube after the venturi, so everything that is part of the skimmer design must be taken into account to get a really well working package.