Using a grounding probe in conjunction with GFCI will never mask a problem, it will only solve them.
There is a huge amount of bad information regarding ground probes in aquarium. It seems like the bad information resolves around 3 main points. First, people don't understand that fish are less conductive than the sea water they live in and don't understand the impact of this. Second, people assume that it takes the same amount of current to drop an induces voltage as it does a traditionally supplied voltage. This is completely false. It takes fractions of an amp to eliminate an induced voltage from an aquarium. Third, people assume that only current impacts fish. This is true of people but people don't have voltage sensors in our heads and lateral lines.
I really need to write an in depth and technical article about this.