Setting Up Your Hot Tub for the First Time

If you’re in a very hard water area, it might be a good idea to invest in a pre-filter for your hose before you fill your hot tub. This will remove some of the minerals that cause high TA (total alkalinity) and will make balancing your chemicals much easier. Without a pre-filter, you will need to use TA reducer (hydrochloric acid) or pH reducer (sodium bisulphate), also known as pH minus.

If you’re in a very soft water area, you will need plenty of TA increaser (bicarbonate of soda), also known as TA plus.

Fill the hot tub with fresh water. When the water covers the jets/air inlets, you can turn on the heater. If you have an inflatable tub and you’re filling from the hot tap, start off with some cold so that the water hitting the tub’s surface isn’t too hot, and make sure to protect any area of the tub where the hose might be touching. When the temperature reaches 20-25 degrees C, take a dip test with a good quality test strip to give you a starting point. When the tub has finished filling and after you’ve got your starting point, always balance your chemicals in the following order:

1. TA – Acts as a buffer for the pH so that when you add other chemicals, such as the sanitiser, the pH doesn’t swing about wildly.
   • The recommended range for TA is 80-120ppm (parts per million or grams per litre)
   • If TA is too low (below 60ppm) there can be rapid changes in pH, corrosion of exposed metal parts, eye irritation and in some cases a coloured tint (usually green) to the water.
   • If TA is too high (above 160ppm), it can lead to the pH being resistant to change and difficult to adjust (“pH lock”). It can also cause cloudy water.
   • To increase TA by 10ppm in 1000 L add 18 g of TA increaser or bicarbonate of soda.
     1. To calculate how much you need for your tub per 10ppm: 18 divided by 1000, multiplied by the volume of your tub.
   • To reduce TA by 10ppm in 1000 L add 22 mL of TA reducer.
     1. To calculate how much you need for your tub per 10ppm: 22 divided by 1000, multiplied by the volume of your tub.
   • Always follow the instructions on the container.
2. pH – The degree of acidity of the water is measured by its pH value on a logarithmic scale of 0-14, with 7 being neutral.
   • The recommended range is pH 7.2 – 7.4.
   • As the pH falls below 7, it becomes more acidic and increasingly corrosive to pool and hot tub parts.
   • If the pH is too low or too high, the water can irritate the skin and mucous membranes.
   • The bactericidal efficiency of most disinfectants is reliant on pH. As the pH rises towards 8, the bactericidal activity of chlorine decreases rapidly.
   • Our Natural Spa Clarifier is less effective if the pH value goes above the recommended range.
3. Sanitiser – only when the first two are within the recommended range should you address the sanitiser.
   • Always start with a shock dose of chlorine on a fresh fill. This will ensure that any bacteria lurking within the hose pipe or the system itself are removed. (You can use stabilised chlorine granules, but it will take longer for the chlorine to reduce and you will be adding stabiliser unnecessarily). Add enough chlorine (follow the guidelines on the container) to maintain free chlorine at 10ppm for at least 5 hours. Then wait for the chlorine level to drop to 3-5ppm (usually over night).
   • After the shock dose of chlorine has decreased, maintain sanitiser level at 3-5ppm Free available chlorine or 4-6ppm Free available bromine, depending on which sanitiser you use. 
4. Pennosan Natural Spa Clarifier – This is the best time to add our Natural Spa Clarifier BUY NOW.
   • Always make sure the pH is in the recommended range before use.
   • If you use fake tan, sunscreen or other lotions, increase the amount of Natural Spa Clarifier and change/wash your filters more frequently.
   • Add a maintenance dose (5-10mls per 1000L) once a week or more often if needed.
   • You can get straight into the tub. No need to wait.
5. Enjoy your hot tub and click here for our guide on routine hot tub water care and maintenance.