We have had this pool now for two years: they claimed they coated this before they sent it. since, when it is filled it chalks over the bottom. We have sanded and re gel 4 times.....it comes back. Last attempt this week. Acetone the wax coating from the bottom....some spots were removed..it appeared come off. fill with water and back again. Now, my question what can i do so i can get a even bottom, spots of blue underneath the wax..and other blue lines ..u can stratch it with a hard brush and see yoru blue. They claim new color. My thought is the siren is coming back through the mold...if i sand again and geal coat with another color, it will be back...what are my options. i have considered tile.. the pool folks have left me behind. HELP 21g fiber pool, Hayward pump, salt system with filter. all the balancing works great....Just the bottom looks crazy....need someone to call.