Bath Ball Replacement Sponge for Crystal Quest® Bath Ball Filter. Crystal Quest® bath ball Filter is the most advanced bath filter on the market. Removes chlorine chloramines VOC's THM's pesticides sulfur heavy metals hydrogen sulfide ("rotten egg" odor) iron oxides ("rust water") dirt sediment and other odors -- and it's pH balanced!! It works in the bath by filtering the water through two stages of KDF. The results? The healthiest most refreshing bath experience ever. It's like bathing in spring water. . Crystal Quest® bath ball Filter will give you smoother softer skin and hair that is less dry. Your tub and shower area will be cleaner too! The unique drop-down filter design allows for a substantial amount of filtration media enabling more contact time with the water. More contact time means better filtration.