Yes you can add more sequestering agent although it may not be needed.
What needs to be done right away is to gently raise the pH. By gently I mean small amounts of chemical, retest, adjust as needed. I would get the pH to about 7.2.
To raise pH you can use borax (20 mule team laundry additive for supermaket). If you already have pH up, then you can use that. You want to keep the iron in solution so a lower pH like 7.2 would be good.
The alk (TA) is fine for now and so is the chlorine. Adding the chlorine (especially in large doses) is usually what brings about the brown water.
The sodium based chlorine you mention is just liquid chlorine you get at a pool store or Home Depot type store. Also, household bleach (unscented) is also sodium based chlorine. Same as the stuff from the pool store but in a lower strength.
To get the brown out you filter, filter, filter (cleaning the filter over and over). The other way is to drain off some of your water and refill. The trouble with that is you're using the same well water that has iron in it.
One thing you might try is turning off your filtering system for the night. This should allow some of the mess to settle out. Slowly vacuum to waste to remove it.
The key, should you ever have clear water again, is to not add too much chlorine too quickly. The chlorine reacts with iron and bingo, brown water again.
Chris B wrote:CL = 7.2
PH = 6.6
ALK = 126
Water is still brown, filter is pathetic brown
Prior to the water turning brown readings were
CL = 1,2
PH = 7.8
ALK = 178
Chemicals that have been added since
Muriatic Acid = 2 Gallons
CL= 1 gallon(liquid)
GLB (Sequa-Sol) = 16oz
Still brown water