How to plug a second washing machine barb?

[Former Workshop member]

Hello, I have recently installed my washing machine in a new property. The drain pipe has two barbs. I have attached the washing machine hose to one barb with a hose clamp and it is working well. How do I plug the second barb (above the connected barb) so that the bubbles don't overflow out? Is there a product for this purpose?

Second barb is circled. How to plug it?

[MitchellMc]

Welcome to the Bunnings Workshop community @Former Workshop member. It's terrific to have you join us, and many thanks for your question about blocking a trap barb.

I apologise for the delay in my reply.

This Deks PVC Trap Dishwasher Outlet Cap will resolve your issue. It simply pushes onto the un-used barb, and the clamp holds it in position. 

Please let me know if you have any questions.

Mitchell