My current Sunsun filter has a 1000 litre ph capacity. I feel, for my 80g tank, it's not powerful enough. The flow rate is, frankly, embarrassing. Looking at the spray bar, it looks like something between 'spraying' and 'dripping' water. My water constantly has some little debris in it, too. I was looking around for a slightly more powerful filter to do my tank at least 4 times per hour. Despite its high price tag, I found that the Fluval FX4 is very suitable because: it is double the flow rate, which will allow me to have extra filtration and also getting rid of the sponge filter that I detest. It's also 8w extra to what I have running right now. So, it won't make much difference in power consumption. That being said, I'm a bit worried the strong flow creating a powerful current in the tank. Which, from experience, I know that my goldfish don't like much. Is the FX4 an overkill for an 80g tank?