I'm still trying to figure out how you got engine coolant in your fuel tank.
It sounds like you are going overboard on the cleaning process. You've done enough. I'd just put fuel and a little biobor in and as someone suggested, use the clear filters so you can keep an eye on things. I don't understand why they even make the opaque ones. If you get fungus again at a later date, kill it with biobor and change the filters. Also if you don't drive the car much, keep the tank topped off. What happens and particularly in humid climates is moist air condenses as the tank cools from the warmer day. What happens on the inside of your big old windshield is what happens in your tank.
Peter