Calcium Hypochlorite should only be used in a pool, you need a shock for the hot tub that is a potasium based shock. I dond't know what brand of chemicals you are using for your hot tub so I can't give you an exact name of the product that you would need. But PLEASE don't use hypochlorite, it is for a pool. Also don't us trichlor, also for a pool! There are different types of chemicals for cold and hot water so you don't want to mix them. Once you do find out which potasium based shock you need to use (the name of it), use it once a week. You normally have to use in a 4-5 person hot tub, 3 oz. of it once a week, when you sprinkle it in the water, leave your cover completely off of the tub like you were using it for 15-20 min with the jets running. If you aren't quite sure what the shock does, here is a brief explination: your sanitizer that you use which could be chlroine, bromine, or a biquanide(which is what bio guard is) is put in the water to kill all the bacterias in the water, but once your sanitizer has killed the bacterias, it falls to the bottom of the tub....you want to shock it once a week and what the shock does is it takes all those dead particles and bacterias that are in your water and turns them into a gas and vents them out of your tub and water. If you have the cover on while doing this, everything will rise to the top of your hot tub cover and fall back down into the water and it coule possibly make your cover slimy on the inside. So there you have it in a nut shell!