We just installed a jetted tub in our newly renovated bathroom. First use get a rust colored skim on top of water line / ring around tub after only 10 minutes of use!!. Cleaned easily , attributed it to possibly not cleaning well enough before first use ... used again next night after extensive clean , same results. Our water is well water, I know it's hard etc but we have sediment filter, carbon filter and softener system. No other shower / sink / toilet / washing machine in the house have comparable stain issues .. HELP??!!