We have two SCAD monitors and the foil has not come unstuck. One of our tanks
is short in height and long in length (rectangle laying on long side). For this tank, the SCAD monitor
is not very accurate from 0-25% when filling, and from 100-75% when emptying. Strangely, it is accurate in the 75-100% when filling. But since it is a holding tank like yours, we are not concerned about accurately knowing the first 25% when filling or the last 25% when emptying.
The other holding tank is the same size, only mounted on the end so it is a tall tank. The SCAD is accurate on that one.