Geebee floats are terrible in that the flex too much.
They will flex under load and allow the aircraft to veer one
way or another. Also they tend to leak as you have found out.
I've had a set of Goldberg wooden floats on a cub for about 12
yrs with no problems, only time they leak is if the cub is crashed.
But nothing wrong with a set of foamcore floats.
Jerry