Are you sure that it is only the hot water that smells? Sometimes its only the smell from the hot water that gets noticed because it is more obvious. Heat from hot water rises and brings the smell with it unlike cold water. Also, mostly hot water is used in showers. Showers have a high volume of water, they steam, mist, and spray also making hot water smells more obvious. A good way to tell for sure if it is only hot water would be to heat some cold water up in the microwave and see if it has a more noticeable smell after it is hot. If you conclude that it is definitely just the hot water, then I think your hot water heater might be the culprit (assuming you do not have a tankless). You may have got some of that silt or sulfur water in there. I would drain and flush out the hot water heater. You could even add some bleach to the hot water heater to get the smell out of there. I have a similar water issues only mine are with iron. I use a different approach to my filtration. I have a Fleck Pyrolox filter that gets rid of iron, sulfur, and manganese. Pyrolox media is a naturally mined ore that oxidizes iron, sulfur, and manganese allowing it to be trapped and filtered by a layer of gravel that is at the bottom of the filter. This filter gets rid of the sediment, silt and most of the smell in my water. I then have a water softener that uses iron out salt and this gets rid of any remaining smell. The problem I have is when the filter goes through its nightly back wash it goes into by-pass mode. During this time if I use hot water I get all that unfiltered iron in my hot water heater. This causes the hot water heater to smell until I bleach it or flush it out. My system works well. The best part is no bleach or chemicals. A similar system might work in your application depending on how much sulfur you have in your water. I think my filter will take out 4 ppm of sulfur. It also takes out the cloudiness and silt in my water. I almost ended up going the bleach route like you did but I did not have the space for the retention tank and did not want to add bleach to my water and then have to remove it with a carbon filter. My system was also a lot cheaper.