notching tank for external overflow

[mark]

A small stream of water would work and if was warmer outside probably would have done that myself but since was in the basement just made a dam. I used duct seal, it's a putty used to fill holes when running wires and pipe but could use play-dough etc. Just kept cutting the groove a little deeper not going all the way through so wouldn't loose the water until the end. With a continous stream wouldn't matter if cut through and would be able to follow line better (not blocked by cuttings).