I have a Neptune COR-20 that I want to connect to my 525. I’ve read elsewhere a hose should have been included; there wasn’t one. The inside diameter of the barbed fitting that came pre-attached to the plumbing is just over 1/2” 13.5mm). The lower portion of the barbed fitting has an outside diameter of just over 3/4” (21mm). I’m assuming a 3/4” inside diameter piece of vinyl tubing will make the connection, (though flow is restricted to 1/2” by the inside diameter of the fitting). Am I correct on the US market tubing size needed? I realize it might need heated to fit but assume a 1” would be too large. Thanks.