I am planning a new build and am leaning toward using a Ghost overflow. I am concerned that a 1 1/2" union will not fit directly beneath (using 4" PVC) the 16" Ghost overflow. The Spears, schedule 80, 1 1/2" union is 3-9/16" in diameter. Will that fit 4" under the overflow without hitting the tank? It isn't a big deal if it is. I'll just drop the plumbing down a few extra inches, reduce it to 1", and use a 1" union. That way I have plenty of room to cut the old union off and add a new one if the need ever arises. I'm just trying to plan ahead. Thanks!