If your pool is already painted, the existing paint type should be determined for compatibility before applying any new paint. This can be determined by sending a sample to Ramuc (or other paint manufcturer) if the paint type is unknown. There are also a few tests you can try. Take a 1 inch paint chip, immerse it in denatured alcohol. If the chip dissolves, it is a water-based acrylic. If it doesn't dissolve, immerse a new chip in 75% mineral spirits and 25% Xylol, wait 30 seconds and rub the chip between your thumb and forefinger. If it dissolves, the paint is a synthetic rubber-base coating. If not, try immersing one last chip in 100% Xylol. If it dissolves, the paint type is chlorinated rubber; if it does not, it is an epoxy. You can see our paint compatibility chart at http://www.inyopools.com/images/pool_paint_compatibility.gif.