My water appears crystal clear but at times when the jets are on we seem to get some tan looking bubbles and some residue at the top of the waterline. What does this mean? We also can't seem to keep a free chlorine reading. For average use of a 500 gal hot tub, is 2 tsp. of Chlorine daily too much or too little? We do have the OZ feature on our tub and the store told us to use 1 tsp of chlorine per week. That seemed way to little to me. Also the directions say to adjust the Alkalinity of the water first and then the PH. When the PH is up I've been adding PH Down. Does Alkalinity Up mean Acid Up. Forgive me for all the questions but I'm so new at this.