Brown pool dampen, but NO metals? I have been tourmented by problems next to my pool since the...

I have been tourmented by problems next to my pool since the start of the year. What I thought to be a metal problem is not. The metal reading is zero for copper and zero for iron. The brown dampen will disapear with a metal/stain remover but does not solve the problem completely, it will be back within about three days. I have have a pool for a long time. I have never seen anything resembling this. I am my pool store's "poster child" and am currently receiving free chemicals, since I have dumped contained by about fivehundred in one month. The relations at the pool store do not know what it is, or what to do. The chemicals I have already used are::: Metal removers, algecides, shock, clarifier's, flocc., filter aid, flocc and vac., I think that's newly about it. Oh, and I changed my sand this past weekend. I want to get rid of the brown. All of my readings are in good range, adjectives now, but ph, just rain alot, getting that back up. Thanks in mortgage to any and all help!
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Answers:    The shock could be adjectives gone after killing the algae. Dump about 8 gallons of fluid chlorine in.
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Use alphamethylcellulose. Its sold as BaqAid or SparkleUp and other brands.

This light fluffy powder coats the sand contained by your filter use it per label and it will remove what is probably manganese or another metal that is not anyone detected.

Turn off your chlorinator and keep lots of trichlor within the skimmer. This will react with the metal and relief it precipitate onto the treated sand bed.

Use the powder as directed until all of it is gone. Very likely it will solve your problem.

Keeping the pH for a time on the high side (7.7) will help precipitate the metal. If you seize a stain, you can drop the pH and start over. If that makes you nervous, afterwards just go next to normal pH.