Hydrogen Sulfide is a mineral that releases a gas that smells like rotten eggs. It also leaves a black coating on your pipes. An inline "so called whole house filter" might trap the particles you are seeing from in front of itself, but not after. The black coating is in suspension, so until it makes a coating and breaks off in little pieces later, the filter doesn't even know it's there. Same for iron. Save your money, or keep buying the cartridges every few months. In my opinion, those filters are a joke.
If you want to filter out iron, a real iron filter will be needed. We sell a filter that removes iron and sulphur without any chemical usage. It uses air only. It will also remove the flakes in front of itself, but not after. All the filter removes from sulphur is the gas that makes your water smell.