Re: How much chlorine will I need to clean a "FL Everglade"
The huge amount of chlorine all at once approach works especially well when the CYA level is relatively high. The CYA will buffer the chlorine and cause it to effectively be added much more slowly. The down side when you do have high CYA levels is that you are left with very high FC levels, which will take a long time to come down to something more reasonable. With CYA down around 30-50 it has some more significant disadvantages, like larger than otherwise chlorine loses to sunlight and possible corrosion and liner fading risks if you go way too far and add much more than enough chlorine.
The rule of thumb I'm familiar with for this approach is to carefully note the color of the water. Then start adding chlorine at a slow and steady rate, pouring slowly in front of a return with the pump running. When the color of the water changes, stop adding chlorine. That means more or less any color change, usually it will be a shift from relatively green towards relatively brown.
I much prefer the add, wait, test, repeat approach. It is a little more work, but it saves on chlorine and is just as effective.