Polyfill did not turn brown after 3 days of filtering

[borjis]

I have traces of iron in my city water supply.
Every other year, the water turns green when the first chlorine of the year is added.
This was supposed to be a "clear" no green year. But it wasn't, it turned green but
not a dark green as usual. In fact, it is green enough that I can definitely tell, but a photo
taken you cannot see it. I ran the pump for 3 days and it seems like it has lightened up,
but I just took all the polyfill out of the skimmer and there is not a trace of brown or orange.

Is this normal at this low of iron levels to have iron filtering and being caught, but not making the polyfill brown?
I got a bottle of jacks magic pink stuff (the liner is stained a bit brownish from over the years) but would
rather not have to keep dosing the pool all summer, if at all possible.

In previous years I would just do a 60/40 water swap and that would make the water clear up completely. (same source iron is from, makes ZERO sense, but it does clear up every time)
Water here is not as expensive as across town, but I'd like to not go that route anymore. Least cost method preferable.

thanks!

 

[ajw22]

Polyfill will only capture iron that has precipitated out of soluble form in water.

Iron Fill Water Filter - Further Reading

www.troublefreepool.com

Visible versus Soluble Iron
Filtering visible iron does not necessarily remove iron from your pool. In fact, a normal pool filter is very likely capable of filtering out visible iron.[

The iron that causes most of our pool issues is iron in soluble form and passes right through mechanical filtration. Then, a combination of conditions can occur in your pool that allows that soluble iron to precipitate out onto your pool surfaces and it bonds tightly to those surfaces.........making removable quite difficult.

Filtering visible iron can be done mechanically. Soluble iron is not so easy and, generally speaking, will pass through any attempts at mechanical filtration.

Sequestrants keep iron in soluble form - preventing them from precipitating on your pool surface - but the iron is still there.

R/O treatments actually remove the soluble iron but they do so through mechanical filtration

 

[borjis]

Well that's good. I took the advice from others doing this and raised it to shock level for my cya level.
It turned green so it's visibly out of solution. I'm just wondering why I am not seeing anything in the polyfill
as the water has less green than it had last weekend and seems to be getting lighter each day. I guess I should
feel fortunate that it appears to be going away via polyfill. I suppose it might not visibly register due to how
low ppm of iron I have. One other person reported this same exact situation. Green changed to blue, but
no orange or brown streaks in the polyfill. Their water was not brown or dark green either.

 

[borjis]

Welp after a cumulative pump run time of roughly 36 hrs, the water is now fully blue / clear. Keeping near shock and with skimmer basket stuffed with polyfill the entire time. Excellent!