Yes the roots don't need to sit in the water for 15 minutes. That's the reason I use
grow rocks so they can sit in water without getting root rot.
That's why I am still waiting for some online member to put together an inexpensive cycle timer that I can sell for them with my gardens.
A 1 gallon safety cap will fit into a 2 1/2 inch tee if you use a 2 1/2 thin wall insert which you may have a hard time finding outside Florida.