How do I get rid of this brownish-whitish foam permanently from the surface of my pool?
599698
Try using a pro-biotic product. The bacteria in the product digests waste. They use this in commercial ponds for cleaning before restocking, and also in oil spills, because it can digest petrol. Ask your local house and garden supplies shop, or if you live near farms ask them.
335293
Freeze dry it. Start by flashfreezing in your favorite cryogen (such as liquid nitrogen) then put it in a vacuum chambger and wait a couple of days.\n\nFreeze drying does a nice job of preserving the structure of the material while getting rid of essentially all the water.
453467
Make a solution of white vinegar and alcohol (equal parts).  Put a couple of drops in each ear when you get out of the pool.  It kills any bacteria and dries the water.
245632
We have had both above ground and in ground pools.  The above ground was easier to care for but I would not recommend baking soda.  We found the most economical way, believe it or not, was a good pool company.  It can be a real headache and expensive to balance those chemicals yourself.  Check with a reliable company and you might be as surprised as we were.  You might also want to check out the Arm & Hammer website that says it's OK if PH level low.
141140
Get rid of debris that retains moisture.
337022
Baking soda and peroxide. Make a paste out of it and brush once a week.
345822
wash it again and put bleach on it\n\nor use a tide bleach pen thing\n\nor use white out
1090037
let it dry, then shake the sand out =]
110030
use carpet deodorizer let it dry then try febreeze.
318669
The obvious answer "by destillation" is technically challenging. I know of a Danish firm EnvoTech ApS that built systems which concentrate problematic waste water by cyclical destillation with very little energy loss,  which would help concentrate the remaining acid, but only up to a degree where the stainless steel the system is built from begins to corrode, and without removing the discoloration. You'd get quite good water condensate to reuse in the process, which isn't that helpful for your problem...\n\nThe foamy particles might be removable by letting the water go through a flotation trough. The resulting acid will still be weak and brown, though.
453542
Hydrogen Peroxide will get it out.
639330
Inorganic materials like copper, iron, manganese, calcium or aluminum can also cloud or discolor the pool water and stain or scale the pool surfaces, especially the plaster and tile grout. When a precipitated metallic salt such as calcium or magnesium remains in suspension, it can cause turbidity or cloudiness of the water. When heavy metal minerals are in suspension, they'll color the water. When these minerals quit floating around and decide to attach themselves or deposit on interior pool surfaces, the mineral salts such as carbonates of magnesium and calcium form a whitish crystallized deposit known as scale. If the precipitated minerals have color, as heavy metals often do, they will deposit themselves in the form of a stain.
926467
Use a Q-tip and apply it directly to it.. it will dry the area...
1131518
drain your pool to below the stain and scrub it with bleach
574415
What do you want to treat it for? Do you wnat to soften it? Remove salt? Sterilise it? Remove pesticides? Remove colloids?\n\nNothing short of an activated charcoal filter or distillation will do al those things
532427
With a water softener.\n\nhttp://en.wikipedia.org/wiki/Water_softener
671685
USadvanage wonder cleaner, or an equivalent citrus cleaner should work.