I found a very very good instruction on cleaning fluorite from some website by fluke. Here's what I did.
Do this on a warm sunny day outside. However, it's possible inside as I did this in the winter and just used the Laundry tub.
1. Put the fluorite in a bucket and use a hose to blast the fluorite with water
2. Pour out the dark water and repeat the process until you can see through the water and the fluorite. When I did this the water was still quite murky but I could see the fluorite. Kinda.
3. Take a strainer and put the fluorite in there and put it under running water for 10-30s.
4. Spread out the fluorite on another container to dry. You can also use an old towel for this on a sunny day. As I was indoors, I just left the fluorite in a bucket for a day to somewhat dry up. However, it's best if the fluorite is dry when you put it in the tank.
5. Put the fluorite in a tank and place a bowl inside. Slowly fill the bowl and let it overflow onto the fluorite. Keep filling. I removed the bowl when the water was half full and just pointed the hose upwards to fill the tank.
I had to clean the fluorite bit by bit as I had a small 3 gallon bucket. I would put in about 8lbs of fluorite in there at a time. I know this is tedious but in the end it reduces a LOT of headaches in the future.
This is how the tank looked like an hour after it was filled:
It was crystal clear when I woke up the next day.

I just used filter floss in the filter to capture the fine stuff. This really really helped me as this was my very first Aquarium and still quite a noob with these things.
