Grand Water Trine ?

Somebody please explain the concept to me. I've searched everywhere online, and still couldn't find a clear cut explanation of the Grand Trine. Perhaps it pertains to an equal balance of all signs ?

I have three Grand Air Trines and my son has Grand Fire and Grand Earth Trines...so, I have researched the trines a lot.

Generally, trines lend themselves to gifts, being gifted, or having it easy in the area that the element represents: Air -mental/relationships, Water - emotional/spiritual; Fire - action/identity; Earth - stability/practicality (oversimplified for brevity).

Specifically though, I would have to look at the planets involved with the trine.

I thought I had this for a second, but nope. No triangles like that in my chart. The name makes it sound pretty badass.