4mm air line to RO line adapters?

[Yevoc]

Hi,
I am trying to connect my new Coral Box doser to my dosing container and sump with RO line push fit connectors. The doser has 4mm silicon airline.

2 questions. One is there a proper RO line to 4mm adapter? The RO line doesn't seal very tight on the barbs.

Two how in the world do you get the 4mm line on the barbs? I tried soaking them in hot water and craming it on but it is like trying to push cooked pasta.

 

[Water Dog]

Perhaps a 3/16” barb x 1/4” stem adapter would work. 4mm is .157” and 3/16” is .187”. While it’s not perfect, I think it may be close enough to make it worth a try.

https://www.usplastic.com/catalog/item.aspx?itemid=31202