What kind of connection does the output have? Screw, barb?
There is also a click fit fitting with a threaded male connection for a few of the pumps. I used to run a 1500 on my 120 and now run a 2400 on my 315. Amazon had the fittings for each of those pumps. I got both of my pumps off of eBay for a little cheaper than they were offered on amazon. I think the seller was pondgirl or something like that.