Our fill water from a well has trace amounts of Iron and over time it causes stains.
I used Jack's Magic Purple Stuff for 2 seasons in our saline pool and it worked well.
I am currently testing the Blue Wave brand of Super Rust & Scale Remover.
It is an HEDP based sequestering agent at 1/3 the cost of Jack's purple stuff.
The MSDS lists only a proprietary blend; however, the shipping classification UN 3265 and (1-Hydroxyethylidene diphosphonic Acid)
Start-up dosage: 15 oz. per 15,000 gallons. Maintenance dosage: 5 oz. per 15,000 gallons.
For pools with only minor issues with Iron, carefully monitoring PH and regularly adding a sequestering agent seems to be a cost effective solution.
I have also been watching the threads on the new product to the market CULator. While the convenience of this product would be a plus, the annual cost would be much higher than the regular use of a sequestering agent.
PSG