Re: Algae or Stains in my gunite pool
put some vitamin c tablets into an old sock and hold them on the stains. If they are rust they will dissappear. If this is the case and the stains are widespread you can treat the pool with ascorbic acid (1 lb per 10000 gal.) and a sequesterant (according to label directions) to keep them from reoccuring. If you have spot staining then just use the vitamin c in a sock to remove them and add sequesterant to your water. It is best to do this when the pH is about 7.2 (7.0 for fiberglass and plaster pools).
run the filter for about 24 hours and then bring your TA backi in line if it dropped. Then adjust your pH if it dropped but keep it about 7.4. You might find that your FC levels have dropped also. Bring them up about 1 ppm/day until they are in normal range. DO NOT SHOCK THE POOL FOR ABOUT 2 WEEKS.
If the vitamin C does not remove the stains then they are not caused by iron. To see if they are caused by algae put a trichor tab in a sock and use your pool pole to hold it on the stain for about 15 minutes. If the stain is organic it will bleach. If so then you can spot treat with the trichor and brush, brush, brush!
Last edited by waterbear; 07-07-2006 at 10:58 PM.
Retired pool store and commercial pool maintenance guy.
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