Will this work?
https://www.amazon.com/EDGE-INDUSTRIAL-Reducer-SPLICER-Fitting/dp/B07CSGSKY3/ref=sr_1_2?crid=J2IHP0RSX8GJ&keywords=hose+barb+reducer+1%2F2+x+3%2F8&qid=1554670559&s=gateway&sprefix=hose+barb+%2Caps%2C201&sr=8-2