Hot Tub Chemical Dosing Calculator

Enter your hot tub's water volume in litres and get a guide dose in grams for everyday hot tub chemicals - chlorine and bromine sanitisers, shock treatments and water balancers. Every rate mirrors the dosing instructions on the matching ClearSpa product label. Guide doses only: dose, circulate, retest, and always follow the product label.

• Chlorine top-up (stabilised chlorine granules): 1.4 g per 1,000 litres - top-up dose to raise free chlorine by about 1 ppm
• Bromine bank on a fresh fill (bromine granules): 25 g per 1,000 litres - initial dose to establish the bromine bank on a fresh fill
• Bromine tablet dispenser top-up (20 g tablets): 40 g per 1,000 litres - dispenser top-up to hold free bromine at 4-6 ppm
• Weekly non-chlorine shock (MPS): 17 g per 1,000 litres - regular weekly oxidising dose
• Chlorine shock for problem water (calcium hypochlorite): 7.5 g per 1,000 litres - shock dose to deal with algae and heavy cloudiness
• Raise total alkalinity (sodium bicarbonate): 17 g per 1,000 litres - dose to raise total alkalinity by about 10 ppm
• Lower pH and alkalinity (sodium bisulphate): 16 g per 1,000 litres - dose to lower pH by about 0.2 (also reduces alkalinity)