Now, you fill the tub again about ¾ of the way with new water, and dump in potassium peroxymonosulfate crystals or shock crystals and let that run several hours to clean the jet pipes, then you add about 2 cups of bleach for sterilization, you need to get the pH range into the acidic range, bleach is basic, so use the strips and HCl solution (just a couple table spoons of HCl is going to be plenty to get the tub lower than pH 7, so the acid will sterilize any remaining bacteria/biofilm. Let it run with this shock and acid solution for a couple hours with the jets and cover on.
The actual equilibrium occurring when you add dichlor or bleach to water is HCLO ---- CLO- at ph over 8, it’s all in the CLO- form, which doesn’t kill bacteria. HCLO kills bacteria. You can search on line and educate yourself quickly about that. You have to dump the water after 3 months, because the tub builds up salts from adding dichlor and organics from the environment and your body, which do not outgas, and after a while, you can’t control the equilibrium, or the pH, and bacteria will immediately start forming biofilm, which is toxic, causing hot tub rash, fungus and algae infections, or even serious stuff like Legionnaires disease. If the pH of a tub falls higher that 7.8, bacteria will immediately start growing, even in a tub dosed with lots of chlorine products. Lower pH will irritate the skin and you’ll get rash from that too. Once biofilm grows, it’s very hard to get rid of it in a hot tub. That’s why you have to flush and sterilize every three months or so. If you have a funky smell or see white floating toilet paper looking stuff in the water, don’t get in. If you see a ring on the water line, don’t get in, it’s time to add flush, drain, fill and sterilize, drain and then fill and balance the waters 1. Alkalinity 2. pH 3. Hardness, and finally the chlorine levels…..in that order.
The chlorine in a hot tub or a pool will start out gassing as soon as you put it in, even with the cover. In a week or so, the chlorine levels will be gone in a normal hot tub at 100 degrees F. Also, UV rays will destroy chlorine, more so in a pool. In pools, they add cyanuric acid to stabilize the chlorine, but not in hot tubs. The Dichlor has the triazine salt equilibrium, which helps stabilize the chlorine in hot tubs. You have to add dichlor once a week, if you are not using it regularly, more if you are using it regularly. You have to use the strips each time and adjust chlorine levels properly.
You add a little bit of dichlor crystals, let it jet for an hour, then take another reading with the indicator strips, and add more if necessary. Each time you use the pool, you’ve added lots of skin cells and body oils to the tub, so you have to add a teaspoon of dichlor each time, maybe some potassium peroxymonosulfate also to degrade the organics, because bacteria eat organics.
1. The strips measure alkalinity (BUFFER amount). Adjust up with sodium bicarbonate (NaHCO3, baking soda) 3 table spoons in a 400 gallon spa is about right, this establishes a BUFFER, which stabilizes the pH levels. VERY important. You can’t adjust alkalinity down, if you have high alkalinity city water, then you have to filter it before you add to tub. Probably the alkalinity is low from your city water hose. So you’ll have to add bicarb NaHCO3.
continued part 3
