Determine what kind of paint is currently used in your pool. Most likely, it is either chlorinated rubber paint (which has a life span of two to three years) or epoxy paint (which has a life span of five to seven years). The best way to know for sure is to take a chip of the paint to your dealer and have it tested. It is best to continue covering the pool with the same kind of paint already in use.
Determine how many coats of paint are on your pool walls. (Either peel off and count the layers in an area that is flaking or scratch through with a pocketknife to count the layers.) Painting over a coat or two is fine, but you'll likely encounter problems with adhesion if the old paint is thicker than that.
Look into having the surface sandblasted to bare concrete if you're dealing with multiple layers of old paint. Make sure all paint and sand is removed from the pool before painting.
If you're painting over a layer or two of old paint, first apply trisodium phosphate to clean the walls. Scrub thoroughly.
Rinse and follow with a coat of muriatic acid; allow it to soak according to the manufacturer's direction. (Be absolutely certain to protect your eyes, lungs and skin from this acid solution!)
Rinse with more clean water and use another wash of trisodium phosphate to neutralize any acid still on the surface.
Rinse again with fresh water. Pump out all water (See "How to Empty a Swimming Pool" in the Related eHows) and allow the pool to dry completely.
Repair any cracks before painting. (See "How to Patch a Swimming Pool" in the Related eHows.)
Apply most chlorinated rubber paints directly to the surface; these paints are self-priming. Epoxy paints generally need a coat of primer, especially on bare concrete.
Roll the paint on to cover large open areas evenly and quickly. Use a brush for corners and tight spots around drains and inlet and outlet valves.
Carefully follow all manufacturer's drying and curing directions. Temperature is critical to epoxy paints to ensure proper curing and coating. Low temperatures can cause discoloring and poor adhesion.