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.
2. The strips measure pH, or the acidity of the water. AFTER adusting alkalinity (not before) You adjust pH down by adding HCl (hydrochloric acid or common name muratic acid). Adjust pH up by adding Na2CO3 or sodium carbonate or soda ash. Aim for ph of 7.2 to 7.8, this optimizes the killing of bacteria by optimizing the amount of HCLO in the water from the HCLO to CLO- equilibrium.
3. The stips measure water hardness. This is a measure of how much Calcium ion you have in solution, you can buy calcium chloride (not calcium carbonate) in solution or crystal form, I used solution form from hot tub store. My calcium read 0, so I had to add half a bottle of Hardness increaser (CaCl2 calcium choride) solution to bring it into proper range, the indicator strips are color coded on the container to compare. The proper calcium hardness level will help buffer the pH levels which control the chlorine levels. Also, proper hardness will decrease foaming .
4. Chlorine levels. When you first fill the tub after draining it for the second time after shocking and sterilizing with bleach after the flushing procedure, you add a couple tablespoons of Dichlor crystals from Walmart or the hot tub store. You’ll see the chlorine rocket up to the 10 to 20 ppm range, which is too high, so you turn on the jets and let the chlorine outgas until it gets into the 2 to 5 ppm range, color coded on the indicator strip. Then you are ready to use. Each time you use the hot tub, you have to add a half spoon of di chlor. Whether you use it or not, you have to add dichlor weekly.
5. After a couple weeks of adding dichlor, (which is a cyclic organic compound triazine with a couple chlorides on it), upon adding to water, the chlorines are released feeding the HClO equilibrium, and the triazine salt starts building up. At three months, the triazine salt concentration is too high, not to mention all the organics which build up from skin cells and body oil, and you have to empty the hot tub and start over. A way to increase the life of the water, is after the first couple weeks, stop adding dichlor to make Cl2 which makes HClO and start adding bleach which IS Na CLO - HClO. You can buy a gallon of bleach at the grocery. Bleach is basic, so you have to take a pH reading and adjust with HCl if PH goes higher than 7.
