Sequestrants are not a magic bullet, they still require a good bit of work. With a known iron source, your pool is going to build up iron over time and only rain will help you out. So, if at all possible, you should consider a rainwater collection system or try to figure out how to divert some rainwater from your gutters. That will be a huge help. Because metals are present, you want to keep your pH on the low side if possible (below 7.5) and your chlorine as low as practically possible because it is the chlorine that will oxidize the iron into a precipitate. High FC also oxidizes the sequestrant and so you need to dose and replenish the sequestrant on a regular basis to keep the iron in solution. When sequestrants get oxidized and breakdown, they release phosphates into the water and you will get phosphate build up. Phosphates are algae-food and, when trying to run the chlorine on the low side, you create a possibility for algae blooms (high nutrient levels and low sanitizing levels). So, as you see, there are a lot of details here that can make dealing with iron-laden pool water a real pain in the rear.
There is no easy/inexpensive solutions, just patience and persistence in keeping the chemical levels properly balanced. Good luck.