Hi psi, and welcome.
Yes, that Jacks magic is one of the two brands we recommend, and pink is most aggressive with iron. Another fav of mine is Metal Magic by proteam, which has the benefit of adding at a ph of 7.5 plus, so no need to adjust the ph.
Do you use a tft100 or Taylor 2096 for your testing, btw?
With either sequestrant, you may need a lot,depending on your iron level, and you will need to constantly maintain the level by adding weekly or whenever you see signs of iron stainng coming back, eg, the steps.
However, since you're on well (and pond) its worth mentioning that the higher your ppms of iron the tougher it is to manage. Some people truck in water to help dilute, whch can get pricey.
Do you know how many ppms of iron your well has? Do you currently have a softener system for the house?
There are a could of tactics that migh help you get better control.
The first two involve filtering -- for in-pool when the water has already oxidized iron fom either slamming or high ph, you could try the slimebag, a 1 micron filtering bag (
The Slime Bag | The Easiest Way To Maintain Crystal Clear Pool Water. ). That would double as a good filter for the pond water too. Get the attachment to put on your return in pool to try to filter down a bit of the brown.
The second is setting up some sediment-then-iron filters for when you top up. With high well iron, you could use a 10" housing with a 5 micron filter, and attach that one to a smaller 1 micron filter and housing. Here's a link to the big housing - both 5 and 1 micron filters are available.
Pentek 150469 3/4 Scientific
The second tip and the one I now use is to plumb the house water softener to the pool spigot permanently, and upgrade to a dual softener for the ability of constant regeneration. This gets my raw, 2 ppm well water down to about .5 ppm...which can still stain...but then with dilution and sequestrant, etc., it becomes more manageable over time, eg .3, which is roughly where I'm at now.
One other experimental thing I'm looking into that I wouldn't normally recommend but in your case might in the future due to pond water would be alum floc. TFP doesn't normally recommend any kind of floc at all because it asks water treatment problems, can gum up your filter, is a pita to vacuum out to waste, and leaves behind sulphates, which can cause their own problems. BUT I am going to try an exeriment in a bucket test to test removal capability and will let you know how that goes.
One way or the other, the trick s not only to sequester the iron, but to also reduce the build up/concentration of it any way you can. Sequestrant alone will not typically do that.
And its worth mentioning for those with iron that keeping the water perfectly sanitized by sing the TFT FC:cya chart and a good test kit helps avoid problems because then you won ave to slam, which turns the water brown. Its also est to keep ph lower, eg 7.2-7.4ish to hel keep the iron in solution instead of oxidizing