Here's a wierd one

[Tman122]

When I change my water, here in Duluth Minnesota it is always the clearest cleanest looking water you have ever seen. It comes from the tap at PH 7.0 TA 70 at 49 degrees. Yesterday after a drain, extensive cleaning and then a refill I almost stopped halfway full because of an iron color to the water which was new to me. The only thing I can figure is they were doing some work close by where they had to cut into the local water line and they stired up some sediment or something right when I was filling my tub. Weird?

[Brewman]

If you are on municipal water (not a well), then what you suggested is certainly possible.  Happened to me once last year.  I popped the hose in the spa and went off to do something for a few minutes, and came back to a hundred gallons of brown water.  Turns out the city was flushing the water mains in the area, which stirs up iron and temporarily discolors the water.  I drained that water, and refilled when the water ran clear again.  
Brewman

[Chas]

I have had that happen at the showroom several times, at customer's homes many times, but never at home. In the showroom, I had the thing just about full to the top before I saw the color, and a factory rep was there - not HotSpring. He wanted to prove to me the amazing filtering capacity of his spas, so we added a bottle of Metal Gon, turned the jets on to full and went to lunch.

Came back, the water was clear and the filter was brown. Took about as long to get the filter clean as it would have to drain and refill the tub....

[Tman122]

Well that's exactly what I did Chuck. I added some metal gone and closed it up to heat. I didn't look till the next evening and the water was almost perfect. But I did take out the filter to rinse and wow was it brown, but it rinsed right off.