Know Jack? No stains! Now you can identify the correct chemicals to remove metallic pool stains. Follow these simple steps:
Take some "pH Minus" granular acid and pour into an old sock. Wearing gloves, tie up the sock into a knot. Guide the sock onto the stained portion and allow to settle for 30 seconds. If there's any improvement under the sock, your stain is metallic. If nothing happens, your stain is organic.
Jack's Magic Stain Identification Kit helps identify the type of metallic stain, and which chemical will ultimately be most effective.
Take (3) different socks and fill them with Stain Solutions 1, 2 and 3. Place them in order over the stained area. One of the three socks will be extremely effective at lifting the stain. The other two will likely do nothing. If two socks are effective, select the sock that worked the fastest against your particular stain.
Now that you've identified which metal is the culprit, you should order a larger quantity of either Stain Solution #1, 2 or 3. This will reduce the metals into a soluble state, reversing the original oxidation. You should remove as much chlorine from the pool as possible, either turn the chlorinator dial to zero, take out the tablets, or shut down the salt water generator.
Once the metals are soluble, you'll need to use a sequestrant to remove the metals and deposit them into the filter. For fresh-water pools, add 1 Qt Jack's Magic The Blue Stuff per every 20,000 gallons. For saltwater pools, add 1 Qt Jack's Magic The Purple Stuff per every 20,000 gallons.
Now that the metals are gone, you can resume chlorination. It's advisable to not shock the pool for at least 48 hours.
To prevent future reoccurrence, add a metal sequestrant (blue/purple), whenever adding 6" or more of new water.