NZQuilter - I like the idea of incorporating aqua in the sashing but I think you should add another block layout to complete the larger coral triangle corner (either at the top/center or bottom left) so that you can see how the larger corals intersecting will look overall. I'm sure it will be beautiful but am thinking it may change the bus-i-ness or scrappy look of the layout. JMHO
Add/edit: I am certain it will look beautiful however you decide just tossing my novice thought out
Christine