I didn't use it for a background, but i did use it for a piece in my one tank. I scuffed up a 1/4th piece of pvc and painted it with that paint, let it dry over night and stuck it in the water and it started rubbing off... so i took it out, repainted it and then applied a clear coat after letting it dry and hav'nt had any more trouble been under water about 8 months now.